Arrow Research search

Author name cluster

Jendrik Seipp

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

53 papers
2 author rows

Possible papers

53

AAAI Conference 2026 Conference Paper

Symmetry-Aware Transformer Training for Automated Planning

  • Markus Fritzsche
  • Elliot Gestrin
  • Jendrik Seipp

While transformers excel in many settings, their application in the field of automated planning is limited. Prior work like PlanGPT, a state-of-the-art decoder-only transformer, struggles with extrapolation from easy to hard planning problems. This in turn stems from problem symmetries: planning tasks can be represented with arbitrary variable names that carry no meaning beyond being identifiers. This causes a combinatorial explosion of equivalent representations that pure transformers cannot efficiently learn from. We propose a novel contrastive learning objective to make transformers symmetry-aware and thereby compensate for their lack of inductive bias. Combining this with architectural improvements, we show that transformers can be efficiently trained for either plan-generation or heuristic-prediction. Our results across multiple planning domains demonstrate that our symmetry-aware training effectively and efficiently addresses the limitations of PlanGPT.

IJCAI Conference 2025 Conference Paper

Abstraction Heuristics for Classical Planning Tasks with Conditional Effects

  • Martín Pozo
  • Jendrik Seipp

In planning tasks, conditional effects model action outcomes that depend on the current state of the world. Conditional effects are a crucial modeling feature since compiling them away can cause an exponential growth in task size. However, only a few admissible heuristics support them. To add abstraction heuristics to this set, we show how to compute projections, Cartesian abstractions and merge-and-shrink abstractions for tasks with conditional effects. Our experiments show that these heuristics are competitive with, and often surpass, the state-of-the-art for conditional-effect tasks.

NeurIPS Conference 2025 Conference Paper

Classical Planning with LLM-Generated Heuristics: Challenging the State of the Art with Python Code

  • Augusto B. Corrêa
  • André G. Pereira
  • Jendrik Seipp

In recent years, large language models (LLMs) have shown remarkable performance in many problems. However, they fail to plan reliably. Specialized attempts to improve their planning capabilities still produce incorrect plans and fail to generalize to larger tasks. Furthermore, LLMs designed for explicit "reasoning" fail to compete with automated planners while increasing computational costs, which reduces one of the advantages of using LLMs. In this paper, we show how to use LLMs to always generate correct plans, even for out-of-distribution tasks of increasing size. For a given planning domain, we ask an LLM to generate several domain-dependent heuristic functions in the form of Python code, evaluate them on a set of training tasks with a greedy best-first search, and choose the best one. The resulting LLM-generated heuristic functions solve substantially more unseen out-of-distribution test tasks than end-to-end LLM planning, particularly for non-reasoning LLMs. Moreover, they also solve many more tasks than state-of-the-art domain-independent heuristics for classical planning, and are competitive with the strongest learning algorithm for domain-dependent planning. These results are impressive given that our implementation is based on a Python planner and the baselines all build upon highly optimized C++ code. In some domains, the LLM-generated heuristics expand fewer states than the baselines, showing that they are not only efficiently computable but also more informative than the state-of-the-art heuristics. Overall, our results show that sampling a set of planning heuristic functions can significantly improve the planning capabilities of LLMs.

ECAI Conference 2025 Conference Paper

Combining Heuristics and Transition Classifiers in Classical Planning

  • Farid Musayev
  • Dominik Drexler
  • Daniel Gnad 0001
  • Jendrik Seipp

Recent work on learning for classical planning has primarily focused on exclusively employing the learned heuristics or policies. However, no purely learning-based method has consistently outperformed state-of-the-art planners to date. To address this, we return to the research paradigm that integrates learned domain knowledge with traditional, non-learned planning techniques. We propose a novel and simple approach for learning transition classifiers, using tree-based statistical learning over description logic features. In experiments, we evaluate various strategies for integrating learned classifiers with the FF heuristic, a state-of-the-art non-learned heuristic. Our results demonstrate that augmenting classical heuristics with transition classifiers leads to substantial performance improvements. The strongest variant combines classifier-based lookahead search with learned knowledge to avoid transitions into unsolvable states, frequently outperforming state-of-the-art traditional and learning-based planners.

HAXP Workshop 2025 Workshop Paper

Explainable Planning via Counterfactual Task Analysis for the Beluga Challenge and Beyond

  • Elliot Gestrin
  • Gustaf Söderholm
  • Paul Höft
  • Mauricio Salerno
  • Jendrik Seipp
  • Daniel Gnad

The Beluga Challenge, recently organized by the Tuples consortium, offered a track on explainable planning (XAIP), to the best of our knowledge the first XAIP competition to date. Within the setting of the Beluga logistics domain, participants were given a planning task and a plan, and were supposed to answer a query to explain to a human expert certain choices made in the plan. The queries ask about particular state atoms that were achieved and alternatives “why achieve this atom A instead of that atom B? ”, action reordering “can I do A before B instead? ”, or about the consequences of object removal “what happens if we forbid to use object X? ”. In this work, we propose counterfactual reasoning to come up with explanations that answer these queries. We design task reformulations, modifications that alter the input planning task, such that the solutions for the modified task allow to explain the choices made in the initial plan. Our framework generalizes the queries posed in the Beluga challenge. To obtain textual explanations, we employ a large language model (LLM) that allows our system to be used without planning-specific knowledge. We empirically show that solving the modified task is similarly hard as finding a plan for the original task, showing that our approach is efficient for practical usage.

JAIR Journal 2025 Journal Article

Finding Minimal Plan Reductions Using Classical Planning

  • Mauricio Salerno
  • Raquel Fuentetaja
  • Jendrik Seipp

While classical planning research has made tremendous progress in the last decades, many complex tasks can still only be solved suboptimally. The satisficing plans found for these tasks often contain actions that can be removed while maintaining plan validity. Removing such redundant actions is desirable since it can decrease the plan cost and simplify the plan. Reducing a plan to a minimum-cost plan without redundant actions is NP-complete and previous work addressed this problem with a compilation to weighted MaxSAT. In this work, we propose several simple and natural formulations to encode this problem as a classical planning task, and prove that solving the resulting tasks optimally guarantees finding minimal plan reductions. We analyze the relation of the classical planning formulations to the MaxSAT compilation, and prove theoretical properties of the known concept of plan action landmarks. Finally, we evaluate the new approaches experimentally and show that they are competitive with the previous state of the art in minimal plan reduction.

ECAI Conference 2025 Conference Paper

Merging Cartesian Abstractions for Classical Planning

  • Mauricio Salerno
  • Raquel Fuentetaja 0001
  • David Speck 0001
  • Jendrik Seipp

Building a single Cartesian abstraction is usually not enough to obtain an informative heuristic for classical planning. Therefore, state-of-the-art methods decompose the original task into subtasks—for example, one per goal atom—and compute an abstraction for each individual subtask. However, building a single abstraction suffers from diminishing returns, while building multiple abstractions loses information about how to achieve the associated subtasks jointly. We interpolate between these two extremes by first considering subtasks individually and then merging some of the resulting abstractions. We introduce an efficient algorithm for merging pairs of Cartesian abstractions using their refinement hierarchies and show that it yields more informative abstractions in less time than a naive approach. Furthermore, we prove that adding merged abstractions can only improve a cost-partitioned heuristic based on saturated post-hoc optimization and that for maximal heuristic values, we need to keep the individual abstractions. Our experiments show that merging abstractions drastically improves the resulting heuristics.

KR Conference 2025 Conference Paper

Representing Perfect Saturated Cost Partitioning Heuristics in Classical Planning

  • Paul Höft
  • David Speck
  • Jendrik Seipp

Saturated cost partitioning (SCP) is one of the strongest methods for admissibly combining heuristics for optimal classical planning. The quality of an SCP heuristic depends heavily on the order in which its component heuristics are considered. For high accuracy, it is essential to maximize over multiple SCP heuristics computed using different component orders. However, for n component heuristics, even enumerating all n! orders is usually infeasible. Consequently, previous work resorted to using greedy algorithms and local optimization. In contrast, we present the first practical method for computing the perfect SCP heuristic that is equivalent to considering all component orders. We show that a set of SCP heuristics forms an additive disjunctive heuristic, which allows us to concisely represent component orders as a directed acyclic graph. Furthermore, once certain components have been considered, the order of the remaining components often becomes irrelevant. By exploiting this characteristic, we can reduce the size of the heuristic representation by several orders of magnitude in practice. Finally, our work makes it possible to compare the quality of existing SCP methods with that of the perfect SCP heuristic, revealing that existing approximations are nearly optimal for standard benchmarks.

JAIR Journal 2025 Journal Article

Symbolic Search for Cost-Optimal Planning with Expressive Model Extensions

  • David Speck
  • Jendrik Seipp
  • Alvaro Torralba

In classical planning, the task is to derive a sequence of deterministic actions that changes the current fully-observable world state into one that satisfies a set of goal criteria. Algorithms for classical planning are domain-independent, i.e., they are not limited to a particular application and instead can be used to solve different types of reasoning problems. The main language for modeling such problems is the Planning Domain Definition Language (PDDL). Even though it provides many language features for expressing a wide range of planning tasks, most of today’s classical planners, especially optimal ones, support only a small subset of its features. The most widely supported fragment is lifted STRIPS plus types and action costs. While this fragment suffices to model some interesting planning tasks, using it to model more realistic problems often incurs a much higher modeling effort. Even if modeling is possible at all, solving the resulting tasks is often infeasible in practice, as the required encoding size increases exponentially. To address these issues, we show how to support more expressive modeling languages natively in optimal classical planning algorithms. Specifically, we focus on symbolic search, a state-of-the-art search algorithm that operates on sets of world states. We show how to extend symbolic search to support classical planning with conditional effects, axioms, and state-dependent action costs. All of these modeling features are expressive in the sense that compiling them away incurs a significant blow-up, so is it often necessary to support them natively. Except for blind (non-symbolic) search, our new symbolic search is the first optimal classical planning algorithm that supports these three modeling extensions in combination, and it even compares favorably to other state-of-the-art approaches that only support a subset of the extensions.

ICAPS Conference 2024 Conference Paper

Abstraction Heuristics for Factored Tasks

  • Clemens Büchner
  • Patrick Ferber
  • Jendrik Seipp
  • Malte Helmert

One of the strongest approaches for optimal classical planning is A* search with heuristics based on abstractions of the planning task. Abstraction heuristics are well studied in planning formalisms without conditional effects such as SAS+. However, conditional effects are crucial to model many planning tasks compactly. In this paper, we focus on *factored* tasks which allow a specific form of conditional effect, where effects on variable x can only depend on the value of x. We generalize projections, domain abstractions, Cartesian abstractions and the counterexample-guided abstraction refinement method to this formalism. While merge-and-shrink already covers factored task in theory, we provide an implementation that does so. In our experiments, we compare these abstraction-based heuristics to other heuristics supporting conditional effects, as well as symbolic search. On our new benchmark set of factored tasks, pattern database heuristics solve the most problems, followed by symbolic approaches on par with domain abstractions. The more general Cartesian abstractions fall behind in terms of coverage but usually solve problems the fastest among all tested approaches. The generality of merge-and-shrink abstractions does not seem to be beneficial for these factored tasks.

ECAI Conference 2024 Conference Paper

Cost Partitioning for Multiple Sequence Alignment

  • Mika Skjelnes
  • Daniel Gnad 0001
  • Jendrik Seipp

Multiple Sequence Alignment (MSA) is a fundamental problem in computational biology that is used to understand the evolutionary history of protein, DNA, or RNA sequences. An optimal alignment for two sequences can efficiently be found using dynamic programming, but computing optimal alignments for more sequences continues to be a hard problem. A common method to solve MSA problems is A* search with admissible heuristics, computed from subsets of the input sequences. In this paper, we consider MSA from the perspective of cost partitioning and relate the existing heuristics for MSA to uniform cost partitioning and post-hoc optimization, two well-known techniques from the automated planning literature. We show that the MSA heuristics are bounded by uniform cost partitioning and that post-hoc optimization yields strictly dominating heuristics. For a common benchmark set of protein sequences and a set of DNA sequences, we show that the theoretical dominance relations between the heuristics carry over to practical instances.

ECAI Conference 2024 Conference Paper

Dissecting Scorpion: Ablation Study of an Optimal Classical Planner

  • Jendrik Seipp

Currently, one of the predominant approaches for optimal classical planning is A* search with heuristics that partition action costs among several abstractions of the input planning task. One example of this approach is the Scorpion planner, which computes saturated cost partitionings over projections and Cartesian abstractions. Scorpion participated in the International Planning Competition 2023 and achieved the second place in the optimal track. It was only outperformed by the Ragnarok portfolio planner, which includes Scorpion as a component. In this invited paper for the ECAI Frontiers in AI series, we present the components of Scorpion and analyze their contributions to the overall performance in an ablation study. As a result, the paper serves as a short introduction to many of the techniques that are vital for state-of-the-art performance in optimal classical planning.

ICAPS Conference 2024 Conference Paper

Efficiently Computing Transitions in Cartesian Abstractions

  • Jendrik Seipp

Counterexample-guided Cartesian abstraction refinement yields strong heuristics for optimal classical planning. The approach iteratively finds a new abstract solution, checks where it fails for the original task and refines the abstraction to avoid the same failure in subsequent iterations. The main bottleneck of this refinement loop is the memory needed for storing all abstract transitions. To address this issue, we introduce an algorithm that efficiently computes abstract transitions on demand. This drastically reduces the memory consumption and allows us to solve tasks during the refinement loop and during the search that were previously out of reach.

JAIR Journal 2024 Journal Article

Expressing and Exploiting Subgoal Structure in Classical Planning Using Sketches

  • Dominik Drexler
  • Jendrik Seipp
  • Hector Geffner

Width-based planning methods deal with conjunctive goals by decomposing problems into subproblems of low width. Algorithms like SIW thus fail when the goal is not easily serializable in this way or when some of the subproblems have a high width. In this work, we address these limitations by using a simple but powerful language for expressing finer problem decompositions introduced recently by Bonet and Geffner, called policy sketches. A policy sketch R over a set of Boolean and numerical features is a set of sketch rules C → E that express how the values of these features are supposed to change. Like general policies, policy sketches are domain general, but unlike policies, the changes captured by sketch rules do not need to be achieved in a single step. We show that many planning domains that cannot be solved by SIW are provably solvable in low polynomial time with the SIWR algorithm, the version of SIW that employs user-provided policy sketches. Policy sketches are thus shown to be a powerful language for expressing domain-specific knowledge in a simple and compact way and a convenient alternative to languages such as HTNs or temporal logics. Furthermore, they make it easy to express general problem decompositions and prove key properties of them like their width and complexity.

HAXP Workshop 2024 Workshop Paper

NL2Plan: Robust LLM-Driven Planning from Minimal Text Descriptions

  • Elliot Gestrin
  • Marco Kuhlmann
  • Jendrik Seipp

Today's classical planners are powerful, but modeling input tasks in formats such as PDDL is tedious and error-prone. In contrast, planning with Large Language Models (LLMs) allows for almost any input text, but offers no guarantees on plan quality or even soundness. In an attempt to merge the best of these two approaches, some work has begun to use LLMs to automate parts of the PDDL creation process. However, these methods still require various degrees of expert input. We present NL2Plan, the first domain-agnostic offline LLM-driven planning system. NL2Plan uses an LLM to incrementally extract the necessary information from a short text prompt before creating a complete PDDL description of both the domain and the problem, which is finally solved by a classical planner. We evaluate NL2Plan on four planning domains and find that it solves 10 out of 15 tasks - a clear improvement over a plain chain-of-thought reasoning LLM approach, which only solves 2 tasks. Moreover, in two out of the five failure cases, instead of returning an invalid plan, NL2Plan reports that it failed to solve the task. In addition to using NL2Plan in end-to-end mode, users can inspect and correct all of its intermediate results, such as the PDDL representation, increasing explainability and making it an assistive tool for PDDL creation.

PRL Workshop 2024 Workshop Paper

Numeric Reward Machines

  • Kristina Levina
  • Nikolaos Pappas
  • Athanasios Karapantelakis
  • Aneta Vulgarakis Feljan
  • Jendrik Seipp

Reward machines inform reinforcement learning agents about the reward structure of the environment and often drastically speed up the learning process. However, reward machines only accept Boolean features such as robot-reached-gold. Consequently, many inherently numeric tasks cannot profit from the guidance offered by reward machines. To address this gap, we aim to extend reward machines with numeric features such as distance-to-gold. For this, we present two types of reward machines: numeric–Boolean and numeric. In a numeric–Boolean reward machine, distance-to-gold is emulated by two Boolean features distance-to-gold-decreased and robot-reached-gold. In a numeric reward machine, distance-to-gold is used directly alongside the Boolean feature robot-reached-gold. We compare our new approaches to a baseline reward machine in the Craft domain, where the numeric feature is the agent-to-target distance. We use cross-product Q-learning, Q-learning with counter-factual experiences, and the options framework for learning. Our experimental results show that our new approaches significantly outperform the baseline approach. Extending reward machines with numeric features opens up new possibilities of using reward machines in inherently numeric tasks.

ICAPS Conference 2024 Conference Paper

Versatile Cost Partitioning with Exact Sensitivity Analysis

  • Paul Höft
  • David Speck 0001
  • Florian Pommerening
  • Jendrik Seipp

Saturated post-hoc optimization is a powerful method for computing admissible heuristics for optimal classical planning. The approach solves a linear program (LP) for each state encountered during the search, which is computationally demanding. In this paper, we theoretically and empirically analyze to which extent we can reuse an LP solution of one state for another. We introduce a novel sensitivity analysis that can exactly characterize the set of states for which a unique LP solution is optimal. Furthermore, we identify two properties of the underlying LPs that affect reusability. Finally, we introduce an algorithm that optimizes LP solutions to generalize well to other states. Our new algorithms significantly reduce the number of necessary LP computations.

ECAI Conference 2023 Conference Paper

Cartesian Abstractions and Saturated Cost Partitioning in Probabilistic Planning

  • Thorsten Klößner
  • Jendrik Seipp
  • Marcel Steinmetz

Stochastic shortest path problems (SSPs) capture probabilistic planning tasks with the objective of minimizing expected cost until reaching the goal. One of the strongest methods to solve SSPs optimally is heuristic search guided by an admissible (lower-bounding) heuristic function. Recently, probability-aware pattern database (PDB) abstractions have been highlighted as an efficient way of generating such lower bounds, with significant advantages over traditional determinization-based approaches. Here, we follow this work, yet consider a more general type, Cartesian abstractions, which have been used successfully in the classical setting. We show how to construct probability-aware Cartesian abstractions via a counterexample-guided abstraction refinement (CEGAR) loop akin to classical planning. This method is complete, meaning it guarantees convergence to the optimal expected cost if not terminated prematurely. Furthermore, we investigate the admissible combination of multiple such heuristics using saturated cost partitioning (SCP), marking its first application in the probabilistic setting. In our experiments, we show that probability-aware Cartesian abstractions yield much more informative heuristics than their determinization-based counterparts. Finally, we show that SCP yields probability-aware abstraction heuristics that are superior to the previous state of the art.

KR Conference 2023 Conference Paper

Eliminating Redundant Actions from Plans Using Classical Planning

  • Mauricio Salerno
  • Raquel Fuentetaja
  • Jendrik Seipp

Even though automated planning is PSPACE-complete in general, satisficing planners are able to solve large planning tasks quickly. However, the found plans are often far from optimal and may even contain actions that can be removed while maintaining a valid plan. The problem of finding and eliminating the most expensive set of such redundant actions in a plan is NP-complete and there is a compilation to MaxSAT that solves it. Here, we introduce a simple and natural formulation of the problem as a planning task. Solving it with an optimal planner guarantees finding a minimal reduction. Our experiments show that this is competitive with the previous state of the art for optimal action elimination.

ICAPS Conference 2023 Conference Paper

Finding Matrix Multiplication Algorithms with Classical Planning

  • David Speck 0001
  • Paul Höft
  • Daniel Gnad 0001
  • Jendrik Seipp

Matrix multiplication is a fundamental operation of linear algebra, with applications ranging from quantum physics to artificial intelligence. Given its importance, enormous resources have been invested in the search for faster matrix multiplication algorithms. Recently, this search has been cast as a single-player game. By learning how to play this game efficiently, the newly-introduced AlphaTensor reinforcement learning agent is able to discover many new faster algorithms. In this paper, we show that finding matrix multiplication algorithms can also be cast as a classical planning problem. Based on this observation, we introduce a challenging benchmark suite for classical planning and evaluate state-of-the-art planning techniques on it. We analyze the strengths and limitations of different planning approaches in this domain and show that we can use classical planning to find lower bounds and concrete algorithms for matrix multiplication.

PRL Workshop 2023 Workshop Paper

Learning Hierarchical Policies by Iteratively Reducing the Width of Sketch Rules

  • Dominik Drexler
  • Jendrik Seipp
  • Hector Geffner

Hierarchical policies are a key ingredient of intelligent behavior, expressing the different levels of abstraction involved in the solution of a problem. Learning hierarchical policies, however, remains a challenge, as no general learning principles have been identified for this purpose, despite the broad interest and vast literature in both model-free reinforcement learning and model-based planning. In this work, we introduce a principled method for learning hierarchical policies over classical planning domains, with no supervision from small instances. The method is based on learning to decompose problems into subproblems so that the subproblems have a lower complexity as measured by their width. Problems and subproblems are captured by means of sketch rules, and the scheme for reducing the width of sketch rules is applied iteratively until the final sketch rules have zero width and encode a general policy. We evaluate the learning method on a number of classical planning domains, analyze the resulting hierarchical policies, and prove their properties. We also show that learning hierarchical policies by learning and refining sketches iteratively is often more efficient than learning flat general policies in one shot.

KR Conference 2023 Conference Paper

Learning Hierarchical Policies by Iteratively Reducing the Width of Sketch Rules

  • Dominik Drexler
  • Jendrik Seipp
  • Hector Geffner

Hierarchical policies are a key ingredient of intelligent behavior, expressing the different levels of abstraction involved in the solution of a problem. Learning hierarchical policies, however, remains a challenge, as no general learning principles have been identified for this purpose, despite the broad interest and vast literature in both model-free reinforcement learning and model-based planning. In this work, we introduce a principled method for learning hierarchical policies over classical planning domains, with no supervision from small instances. The method is based on learning to decompose problems into subproblems so that the subproblems have a lower complexity as measured by their width. Problems and subproblems are captured by means of sketch rules, and the scheme for reducing the width of sketch rules is applied iteratively until the final sketch rules have zero width and encode a general policy. We evaluate the learning method on a number of classical planning domains, analyze the resulting hierarchical policies, and prove their properties. We also show that learning hierarchical policies by learning and refining sketches iteratively is often more efficient than learning flat general policies in one shot.

ECAI Conference 2023 Conference Paper

PARIS: Planning Algorithms for Reconfiguring Independent Sets

  • Remo Christen
  • Salomé Eriksson
  • Michael Katz 0001
  • Christian J. Muise
  • Alice Petrov
  • Florian Pommerening
  • Jendrik Seipp
  • Silvan Sievers

Combinatorial reconfiguration is the problem of transforming one solution of a combinatorial problem into another, where each transformation may only apply small changes to a solution and may not leave the solution space. An important example is the independent set reconfiguration (ISR) problem, where an independent set of a graph (a subset of its vertices without edges between them) has to be transformed into another by a sequence of transformations that can replace a vertex in the current subset such that the new subset is still an independent set. The 1st Combinatorial Reconfiguration Challenge (CoRe Challenge 2022) was a competition focused on the ISR problem. The PARIS team successfully participated with two solvers that model the ISR problem as a planning task and employ different planning techniques for solving it. In this work, we describe these models and solvers. For a fair comparison to competing ISR approaches, we re-run the entire competition under equal computational conditions. Besides showcasing the success of planning technology, we hope that this work will create a cross-fertilization of the two research fields.

ECAI Conference 2023 Conference Paper

Sensitivity Analysis for Saturated Post-Hoc Optimization in Classical Planning

  • Paul Höft
  • David Speck 0001
  • Jendrik Seipp

Cost partitioning is the foundation of today’s strongest heuristics for optimal classical planning. However, computing a cost partitioning for each evaluated state is prohibitively expensive in practice. Thus, existing approaches make an approximation and compute a cost partitioning only for a set of sampled states, and then reuse the resulting heuristics for all other states evaluated during the search. In this paper, we present exact methods for cost partitioning heuristics based on linear programming that fully preserve heuristic accuracy while minimizing computational cost. Specifically, we focus on saturated post-hoc optimization and establish several sufficient conditions for when reusing a cost partitioning computed for one state preserves the estimates for other states, mainly based on a sensitivity analysis of the underlying linear program. Our experiments demonstrate that our theoretical results transfer into practice, and that our exact cost partitioning algorithms are competitive with the strongest approximations currently available, while usually requiring fewer linear program evaluations.

ICAPS Conference 2022 Conference Paper

Best-First Width Search for Lifted Classical Planning

  • Augusto B. Corrêa
  • Jendrik Seipp

Lifted planners are useful to solve tasks that are too hard to ground. Still, computing informative lifted heuristics is difficult: directly adapting ground heuristics to the lifted setting is often too expensive, and extracting heuristics from the lifted representation can be uninformative. A natural alternative for lifted planners is to use width-based search. These algorithms are among the strongest for ground planning, even the variants that do not access the action model. In this work, we adapt best-first width search to the lifted setting and show that this yields state-of-the-art performance for hard-to-ground planning tasks.

AAAI Conference 2022 Conference Paper

Explainable Planner Selection for Classical Planning

  • Patrick Ferber
  • Jendrik Seipp

Since no classical planner consistently outperforms all others, it is important to select a planner that works well for a given classical planning task. The two strongest approaches for planner selection use image and graph convolutional neural networks. They have the drawback that the learned models are complicated and uninterpretable. To obtain explainable models, we identify a small set of simple task features and show that elementary and interpretable machine learning techniques can use these features to solve roughly as many tasks as the complex approaches based on neural networks.

IJCAI Conference 2022 Conference Paper

Learning and Exploiting Progress States in Greedy Best-First Search

  • Patrick Ferber
  • Liat Cohen
  • Jendrik Seipp
  • Thomas Keller

Previous work introduced the concept of progress states. After expanding a progress state, a greedy best-first search (GBFS) will only expand states with lower heuristic values. Current methods can identify progress states only for a single task and only after a solution for the task has been found. We introduce a novel approach that learns a description logic formula characterizing all progress states in a classical planning domain. Using the learned formulas in a GBFS to break ties in favor of progress states often significantly reduces the search effort.

ICAPS Conference 2022 Conference Paper

Learning Sketches for Decomposing Planning Problems into Subproblems of Bounded Width

  • Dominik Drexler
  • Jendrik Seipp
  • Hector Geffner

Recently, sketches have been introduced as a general language for representing the subgoal structure of instances drawn from the same domain. Sketches are collections of rules of the form C -> E over a given set of features where C expresses Boolean conditions and E expresses qualitative changes. Each sketch rule defines a subproblem: going from a state that satisfies C to a state that achieves the change expressed by E or a goal state. Sketches can encode simple goal serializations, general policies, or decompositions of bounded width that can be solved greedily, in polynomial time, by the SIW_R variant of the SIW algorithm. Previous work has shown the computational value of sketches over benchmark domains that, while tractable, are challenging for domain-independent planners. In this work, we address the problem of learning sketches automatically given a planning domain, some instances of the target class of problems, and the desired bound on the sketch width. We present a logical formulation of the problem, an implementation using the ASP solver Clingo, and experimental results. The sketch learner and the SIW_R planner yield a domain-independent planner that learns and exploits domain structure in a crisp and explicit form.

ICAPS Conference 2022 Conference Paper

New Refinement Strategies for Cartesian Abstractions

  • David Speck 0001
  • Jendrik Seipp

Cartesian counterexample-guided abstraction refinement (CEGAR) yields strong heuristics for optimal classical planning. CEGAR repeatedly finds counterexamples, i. e. , abstract plans that fail for the concrete task. Although there are usually many such abstract plans to choose from, the refinement strategy from previous work is to choose an arbitrary optimal one. In this work, we show that an informed refinement strategy is critical in theory and practice. We demonstrate that it is possible to execute all optimal abstract plans in the concrete task simultaneously, and present methods to minimize the time and number of refinement steps until we find a concrete solution. The resulting algorithm solves more tasks than the previous state of the art for Cartesian CEGAR, both during refinement and when used as a heuristic in an A* search.

ICAPS Conference 2021 Conference Paper

Automatic Instance Generation for Classical Planning

  • Álvaro Torralba
  • Jendrik Seipp
  • Silvan Sievers

The benchmarks from previous International Planning Competitions (IPCs) are the de-facto standard for evaluating planning algorithms. The IPC set is both a collection of planning domains and a selection of instances from these domains. Most of the domains come with a parameterized generator that generates new instances for a given set of parameter values. Due to the steady progress of planning research some of the instances that were generated for past IPCs are inadequate for evaluating current planners. To alleviate this problem, we introduce Autoscale, an automatic tool that selects instances for a given domain. Autoscale takes into account constraints from the domain designer as well as the performance of current planners to generate an instance set of appropriate difficulty, while avoiding too much bias with respect to the considered planners. We show that the resulting benchmark set is superior to the IPC set and has the potential of improving empirical evaluation of planning research.

ICAPS Conference 2021 Conference Paper

Dantzig-Wolfe Decomposition for Cost Partitioning

  • Florian Pommerening
  • Thomas Keller 0001
  • Valentina Halasi
  • Jendrik Seipp
  • Silvan Sievers
  • Malte Helmert

Optimal cost partitioning can produce high quality heuristic estimates even from small abstractions. It can be computed with a linear program (LP) but the size of this LP often makes this impractical. Recent work used Lagrangian decomposition to speed up the computation. Here we use a different decomposition technique called Dantzig-Wolfe decomposition to tackle the problem. This gives new insights into optimal cost partitioning and has several advantages over Lagrangian decomposition: our method detects when a cost partition is optimal; it can deal with general cost functions; and it does not consider abstractions in the linear program that do not contribute to the heuristic value. We also show the advantage of the method empirically and investigate several improvements that are useful for all cost partitioning methods.

KR Conference 2021 Conference Paper

Expressing and Exploiting the Common Subgoal Structure of Classical Planning Domains Using Sketches

  • Dominik Drexler
  • Jendrik Seipp
  • Hector Geffner

Width-based planning methods deal with conjunctive goals by decomposing problems into subproblems of low width. Algorithms like SIW thus fail when the goal is not easily serializable in this way or when some of the subproblems have a high width. In this work, we address these limitations by using a simple but powerful language for expressing finer problem decompositions introduced recently by Bonet and Geffner, called policy sketches. A policy sketch R over a set of Boolean and numerical features is a set of sketch rules that express how the values of these features are supposed to change. Like general policies, policy sketches are domain general, but unlike policies, the changes captured by sketch rules do not need to be achieved in a single step. We show that many planning domains that cannot be solved by SIW are provably solvable in low polynomial time with the SIW_R algorithm, the version of SIW that employs user-provided policy sketches. Policy sketches are thus shown to be a powerful language for expressing domain-specific knowledge in a simple and compact way and a convenient alternative to languages such as HTNs or temporal logics. Furthermore, they make it easy to express general problem decompositions and prove key properties of them like their width and complexity.

IJCAI Conference 2021 Conference Paper

Learning Generalized Unsolvability Heuristics for Classical Planning

  • Simon Ståhlberg
  • Guillem Francès
  • Jendrik Seipp

Recent work in classical planning has introduced dedicated techniques for detecting unsolvable states, i. e. , states from which no goal state can be reached. We approach the problem from a generalized planning perspective and learn first-order-like formulas that characterize unsolvability for entire planning domains. We show how to cast the problem as a self-supervised classification task. Our training data is automatically generated and labeled by exhaustive exploration of small instances of each domain, and candidate features are automatically computed from the predicates used to define the domain. We investigate three learning algorithms with different properties and compare them to heuristics from the literature. Our empirical results show that our approach often captures important classes of unsolvable states with high classification accuracy. Additionally, the logical form of our heuristics makes them easy to interpret and reason about, and can be used to show that the characterizations learned in some domains capture exactly all unsolvable states of the domain.

ICAPS Conference 2021 Conference Paper

Online Saturated Cost Partitioning for Classical Planning

  • Jendrik Seipp

Cost partitioning is a general method for admissibly summing up heuristic estimates for optimal state-space search. Most cost partitioning algorithms can optimize the resulting cost-partitioned heuristic for a specific state. Since computing a new cost-partitioned heuristic for each evaluated state is usually too expensive in practice, the strongest planners based on cost partitioning over abstraction heuristics precompute a set of cost-partitioned heuristics before the search and maximize over their estimates during the search. This makes state evaluations very fast, but since there is no better termination criterion than a time limit, it requires a long precomputation phase, even for the simplest planning tasks. A prototypical example for this is the Scorpion planner which computes saturated cost partitionings over abstraction heuristics offline before the search. Using Scorpion as a case study, we show that by incrementally extending the set of cost-partitioned heuristics online during the search, we drastically speed up the planning process and even often solve more tasks.

AAAI Conference 2021 Conference Paper

Saturated Post-hoc Optimization for Classical Planning

  • Jendrik Seipp
  • Thomas Keller
  • Malte Helmert

Saturated cost partitioning and post-hoc optimization are two powerful cost partitioning algorithms for optimal classical planning. The main idea of saturated cost partitioning is to give each considered heuristic only the fraction of remaining operator costs that it needs to prove its estimates. We show how to apply this idea to post-hoc optimization and obtain a heuristic that dominates the original both in theory and on the IPC benchmarks.

ICAPS Conference 2021 Conference Paper

Subset-Saturated Transition Cost Partitioning

  • Dominik Drexler
  • Jendrik Seipp
  • David Speck 0001

Cost partitioning admissibly combines the information from multiple heuristics for optimal state-space search. One of the strongest cost partitioning algorithms is saturated cost partitioning. It considers the heuristics in sequence and assigns to each heuristic the minimal fraction of the remaining costs that are needed for preserving all heuristic estimates. Saturated cost partitioning has recently been generalized in two directions: first, by allowing to use different costs for the transitions induced by the same operator, and second, by preserving the heuristic estimates for only a subset of states. In this work, we unify these two generalizations and show that the resulting subset-saturated transition cost partitioning algorithm usually yields stronger heuristics than the two generalizations by themselves.

SoCS Conference 2020 Conference Paper

An Atom-Centric Perspective on Stubborn Sets

  • Gabriele Röger
  • Malte Helmert
  • Jendrik Seipp
  • Silvan Sievers

Stubborn sets are an optimality-preserving pruning technique for factored state-space search, for example in classical planning. Their applicability is limited by their computational overhead. We describe a new algorithm for computing stubborn sets that is based on the state variables of the state space, while previous algorithms are based on its actions. Typical factored state spaces tend to have far fewer state variables than actions, and therefore our new algorithm is much more efficient than the previous state of the art, making stubborn sets a viable technique in many cases where they previously were not.

ICAPS Conference 2020 Conference Paper

Incremental Search for Counterexample-Guided Cartesian Abstraction Refinement

  • Jendrik Seipp
  • Samuel von Allmen
  • Malte Helmert

Counterexample-guided Cartesian abstraction refinement has been shown to yield informative heuristics for optimal classical planning. The algorithm iteratively finds an abstract solution and uses it to decide how to refine the abstraction. Since the abstraction grows in each step, finding solutions is the main bottleneck of the refinement loop. We cast the refinements as an incremental search problem and show that this drastically reduces the time for computing abstractions.

JAIR Journal 2020 Journal Article

Saturated Cost Partitioning for Optimal Classical Planning

  • Jendrik Seipp
  • Thomas Keller
  • Malte Helmert

Cost partitioning is a method for admissibly combining a set of admissible heuristic estimators by distributing operator costs among the heuristics. Computing an optimal cost partitioning, i.e., the operator cost distribution that maximizes the heuristic value, is often prohibitively expensive to compute. Saturated cost partitioning is an alternative that is much faster to compute and has been shown to yield high-quality heuristics. However, its greedy nature makes it highly susceptible to the order in which the heuristics are considered. We propose a greedy algorithm to generate orders and show how to use hill-climbing search to optimize a given order. Combining both techniques leads to significantly better heuristic estimates than using the best random order that is generated in the same time. Since there is often no single order that gives good guidance on the whole state space, we use the maximum of multiple orders as a heuristic that is significantly better informed than any single-order heuristic, especially when we actively search for a set of diverse orders.

IJCAI Conference 2019 Conference Paper

Pattern Selection for Optimal Classical Planning with Saturated Cost Partitioning

  • Jendrik Seipp

Pattern databases are the foundation of some of the strongest admissible heuristics for optimal classical planning. Experiments showed that the most informative way of combining information from multiple pattern databases is to use saturated cost partitioning. Previous work selected patterns and computed saturated cost partitionings over the resulting pattern database heuristics in two separate steps. We introduce a new method that uses saturated cost partitioning to select patterns and show that it outperforms all existing pattern selection algorithms.

ICAPS Conference 2019 Conference Paper

Subset-Saturated Cost Partitioning for Optimal Classical Planning

  • Jendrik Seipp
  • Malte Helmert

Cost partitioning is a method for admissibly adding multiple heuristics for state-space search. Saturated cost partitioning considers the given heuristics in sequence, assigning to each heuristic the minimum fraction of remaining costs that it needs to preserve its estimates for all states. We generalize saturated cost partitioning by allowing to preserve the heuristic values of only a subset of states and show that this often leads to stronger heuristics.

JAIR Journal 2018 Journal Article

Counterexample-Guided Cartesian Abstraction Refinement for Classical Planning

  • Jendrik Seipp
  • Malte Helmert

Counterexample-guided abstraction refinement (CEGAR) is a method for incrementally computing abstractions of transition systems. We propose a CEGAR algorithm for computing abstraction heuristics for optimal classical planning. Starting from a coarse abstraction of the planning task, we iteratively compute an optimal abstract solution, check if and why it fails for the concrete planning task and refine the abstraction so that the same failure cannot occur in future iterations. A key ingredient of our approach is a novel class of abstractions for classical planning tasks that admits efficient and very fine-grained refinement. Since a single abstraction usually cannot capture enough details of the planning task, we also introduce two methods for producing diverse sets of heuristics within this framework, one based on goal atoms, the other based on landmarks. In order to sum their heuristic estimates admissibly we introduce a new cost partitioning algorithm called saturated cost partitioning. We show that the resulting heuristics outperform other state-of-the-art abstraction heuristics in many benchmark domains.

ICAPS Conference 2017 Conference Paper

A Comparison of Cost Partitioning Algorithms for Optimal Classical Planning

  • Jendrik Seipp
  • Thomas Keller 0001
  • Malte Helmert

Cost partitioning is a general and principled approach for constructing additive admissible heuristics for state-space search. Cost partitioning approaches for optimal classical planning include optimal cost partitioning, uniform cost partitioning, zero-one cost partitioning, saturated cost partitioning, post-hoc optimization and the canonical heuristic for pattern databases. We compare these algorithms theoretically, showing that saturated cost partitioning dominates greedy zero-one cost partitioning. As a side effect of our analysis, we obtain a new cost partitioning algorithm dominating uniform cost partitioning. We also evaluate these algorithms experimentally on pattern databases, Cartesian abstractions and landmark heuristics, showing that saturated cost partitioning is usually the method of choice on the IPC benchmark suite.

SoCS Conference 2017 Conference Paper

Better Orders for Saturated Cost Partitioning in Optimal Classical Planning

  • Jendrik Seipp

Cost partitioning is a general method for adding multiple heuristic values admissibly. In the setting of optimal classical planning, saturated cost partitioning has recently been shown to be the cost partitioning algorithm of choice for pattern database heuristics found by hill climbing, systematic pattern database heuristics and Cartesian abstraction heuristics. To evaluate the synergy of the three heuristic types, we compute the saturated cost partitioning over the combined sets of heuristics and observe that the resulting heuristic is outperformed by the heuristic that simply maximizes over the three saturated cost partitioning heuristics computed separately for each heuristic type. Our new algorithm for choosing the orders in which saturated cost partitioning considers the heuristics allows us to compute heuristics outperforming not only the maximizing heuristic but even state-of-the-art planners.

AAAI Conference 2017 Conference Paper

Narrowing the Gap Between Saturated and Optimal Cost Partitioning for Classical Planning

  • Jendrik Seipp
  • Thomas Keller
  • Malte Helmert

In classical planning, cost partitioning is a method for admissibly combining a set of heuristic estimators by distributing operator costs among the heuristics. An optimal cost partitioning is often prohibitively expensive to compute. Saturated cost partitioning is an alternative that is much faster to compute and has been shown to offer high-quality heuristic guidance on Cartesian abstractions. However, its greedy nature makes it highly susceptible to the order in which the heuristics are considered. We show that searching in the space of orders leads to significantly better heuristic estimates than with previously considered orders. Moreover, using multiple orders leads to a heuristic that is significantly better informed than any single-order heuristic. In experiments with Cartesian abstractions, the resulting heuristic approximates the optimal cost partitioning very closely.

IJCAI Conference 2016 Conference Paper

Correlation Complexity of Classical Planning Domains

  • Jendrik Seipp
  • Florian Pommerening
  • Gabriele R
  • ouml; ger
  • Malte Helmert

We analyze how complex a heuristic function must be to directly guide a state-space search algorithm towards the goal. As a case study, we examine functions that evaluate states with a weighted sum of state features. We measure the complexity of a domain by the complexity of the required features. We analyze conditions under which the search algorithm runs in polynomial time and show complexity results for several classical planning domains.

IJCAI Conference 2016 Conference Paper

State-Dependent Cost Partitionings for Cartesian Abstractions in Classical Planning

  • Thomas Keller
  • Florian Pommerening
  • Jendrik Seipp
  • Florian Gei
  • szlig; er
  • Robert Mattm
  • uuml; ller

Abstraction heuristics are a popular method to guide optimal search algorithms in classical planning. Cost partitionings allow to sum heuristic estimates admissibly by distributing action costs among the heuristics. We introduce state-dependent cost partitionings which take context information of actions into account, and show that an optimal state-dependent cost partitioning dominates its state-independent counterpart. We demonstrate the potential of our idea with a state-dependent variant of the recently proposed saturated cost partitioning, and show that it has the potential to improve not only over its state-independent counterpart, but even over the optimal state-independent cost partitioning. Our empirical results give evidence that ignoring the context of actions in the computation of a cost partitioning leads to a significant loss of information.

AAAI Conference 2015 Conference Paper

Automatic Configuration of Sequential Planning Portfolios

  • Jendrik Seipp
  • Silvan Sievers
  • Malte Helmert
  • Frank Hutter

Sequential planning portfolios exploit the complementary strengths of different planners. Similarly, automated algorithm configuration tools can customize parameterized planning algorithms for a given type of tasks. Although some work has been done towards combining portfolios and algorithm configuration, the problem of automatically generating a sequential planning portfolio from a parameterized planner for a given type of tasks is still largely unsolved. Here, we present Cedalion, a conceptually simple approach for this problem that greedily searches for the hparameter configuration, runtimei pair which, when appended to the current portfolio, maximizes portfolio improvement per additional runtime spent. We show theoretically that Cedalion yields portfolios provably within a constant factor of optimal for the training set distribution. We evaluate Cedalion empirically by applying it to construct sequential planning portfolios based on component planners from the highly parameterized Fast Downward (FD) framework. Results for a broad range of planning settings demonstrate that – without any knowledge of planning or FD – Cedalion constructs sequential FD portfolios that rival, and in some cases substantially outperform, manually-built FD portfolios.

AAAI Conference 2015 Conference Paper

From Non-Negative to General Operator Cost Partitioning

  • Florian Pommerening
  • Malte Helmert
  • Gabriele Röger
  • Jendrik Seipp

Operator cost partitioning is a well-known technique to make admissible heuristics additive by distributing the operator costs among individual heuristics. Planning tasks are usually defined with non-negative operator costs and therefore it appears natural to demand the same for the distributed costs. We argue that this requirement is not necessary and demonstrate the benefit of using general cost partitioning. We show that LP heuristics for operator-counting constraints are cost-partitioned heuristics and that the state equation heuristic computes a cost partitioning over atomic projections. We also introduce a new family of potential heuristics and show their relationship to general cost partitioning.

ICAPS Conference 2015 Conference Paper

New Optimization Functions for Potential Heuristics

  • Jendrik Seipp
  • Florian Pommerening
  • Malte Helmert

Potential heuristics, recently introduced by Pommerening et al. , characterize admissible and consistent heuristics for classical planning as a set of declarative constraints. Every feasible solution for these constraints defines an admissible heuristic, and we can obtain heuristics that optimize certain criteria such as informativeness by specifying suitable objective functions. The original paper only considered one such objective function: maximizing the heuristic value of the initial state. In this paper, we explore objectives that attempt to maximize heuristic estimates for all states (reachable and unreachable), maximize heuristic estimates for a sample of reachable states, maximize the number of detected dead ends, or minimize search effort. We also search for multiple heuristics with complementary strengths that can be combined to obtain even better heuristics.

ICAPS Conference 2014 Conference Paper

Diverse and Additive Cartesian Abstraction Heuristics

  • Jendrik Seipp
  • Malte Helmert

We have recently shown how counterexample-guided abstraction refinement can be used to derive informative Cartesian abstraction heuristics for optimal classical planning. In this work we introduce two methods for producing diverse sets of heuristics within this framework, one based on goal facts, the other based on landmarks. In order to sum the heuristic estimates admissibly we present a novel way of finding cost partitionings for explicitly represented abstraction heuristics. We show that the resulting heuristics outperform other state-of-the-art abstraction heuristics on many benchmark domains.

ICAPS Conference 2013 Conference Paper

Counterexample-Guided Cartesian Abstraction Refinement

  • Jendrik Seipp
  • Malte Helmert

Counterexample-guided abstraction refinement (CEGAR) is a method for incrementally computing abstractions of transition systems. We propose a CEGAR algorithm for computing abstraction heuristics for optimal classical planning. Starting from a coarse abstraction of the planning task, we iteratively compute an optimal abstract solution, check if and why it fails for the concrete planning task and refine the abstraction so that the same failure cannot occur in future iterations. A key ingredient of our approach is a novel class of abstractions for classical planning tasks that admits efficient and very fine-grained refinement. Our implementation performs tens of thousands of refinement steps in a few minutes and produces heuristics that are often significantly more accurate than pattern database heuristics of the same size.

ICAPS Conference 2012 Conference Paper

Learning Portfolios of Automatically Tuned Planners

  • Jendrik Seipp
  • Manuel Braun
  • Johannes Garimort
  • Malte Helmert

Portfolio planners and parameter tuning are two ideas that have recently attracted significant attention in the domain-independent planning community. We combine these two ideas and present a portfolio planner that runs automatically configured planners. We let the automatic parameter tuning framework ParamILS find fast configurations of the Fast Downward planning system for a number of planning domains. Afterwards we learn a portfolio of those planner configurations. Evaluation of our portfolio planner on the IPC 2011 domains shows that it has a significantly higher IPC score than the winner of the sequential satisficing track.

v2026.09.13