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Joohyung Lee

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.

32 papers
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32

AAAI Conference 2025 Conference Paper

LLM+AL: Bridging Large Language Models and Action Languages for Complex Reasoning About Actions

  • Adam Ishay
  • Joohyung Lee

Large Language Models (LLMs) have made significant strides in various intelligent tasks but still struggle with complex action reasoning tasks that require systematic search. To address this limitation, we propose a method that bridges the natural language understanding capabilities of LLMs with the symbolic reasoning strengths of action languages. Our approach, termed LLM+AL, leverages the LLM's strengths in semantic parsing and commonsense knowledge generation alongside the action language's proficiency in automated reasoning based on encoded knowledge. We compare LLM+AL against state-of-the-art LLMs, including ChatGPT-4, Claude 3 Opus, Gemini Ultra 1.0, and o1-preview, using benchmarks for complex reasoning about actions. Our findings indicate that, although all methods exhibit errors, LLM+AL, with relatively minimal human corrections, consistently leads to correct answers, whereas standalone LLMs fail to improve even with human feedback. LLM+AL also contributes to automated generation of action languages.

KR Conference 2023 Conference Paper

Leveraging Large Language Models to Generate Answer Set Programs

  • Adam Ishay
  • Zhun Yang
  • Joohyung Lee

Large language models (LLMs), such as GPT-3 and GPT-4, have demonstrated exceptional performance in various natural language processing tasks and have shown the ability to solve certain reasoning problems. However, their reasoning capabilities are limited and relatively shallow, despite the application of various prompting techniques. In contrast, formal logic is adept at handling complex reasoning, but translating natural language descriptions into formal logic is a challenging task that non-experts struggle with. This paper proposes a neuro-symbolic method that combines the strengths of large language models and answer set programming. Specifically, we employ an LLM to transform natural language descriptions of logic puzzles into answer set programs. We carefully design prompts for an LLM to convert natural language descriptions into answer set programs in a step by step manner. Surprisingly, with just a few in-context learning examples, LLMs can generate reasonably complex answer set programs. The majority of errors made are relatively simple and can be easily corrected by humans, thus enabling LLMs to effectively assist in the creation of answer set programs.

IJCAI Conference 2020 Conference Paper

NeurASP: Embracing Neural Networks into Answer Set Programming

  • Zhun Yang
  • Adam Ishay
  • Joohyung Lee

We present NeurASP, a simple extension of answer set programs by embracing neural networks. By treating the neural network output as the probability distribution over atomic facts in answer set programs, NeurASP provides a simple and effective way to integrate sub-symbolic and symbolic computation. We demonstrate how NeurASP can make use of a pre-trained neural network in symbolic computation and how it can improve the neural network's perception result by applying symbolic reasoning in answer set programming. Also, NeurASP can make use of ASP rules to train a neural network better so that a neural network not only learns from implicit correlations from the data but also from the explicit complex semantic constraints expressed by the rules.

KR Conference 2018 Conference Paper

A Model-Based Approach to Visual Reasoning on CNLVR Dataset

  • Shailaja Sampat
  • Joohyung Lee

Visual Reasoning requires an understanding of complex compositional images and common-sense reasoning about sets of objects, quantities, comparisons, and spatial relationships. This paper presents a semantic parser that combines Computer Vision (CV), Natural Language Processing (NLP) and Knowledge Representation & Reasoning (KRR) to automatically solve visual reasoning problems from the Cornell Natural Language Visual Reasoning (CNLVR) dataset. Unlike the data-driven approaches applied to the same dataset, our system does not require any training but is guided by the knowledge base that is manually constructed. The system demonstrates robust overall performance which is also time and space efficient. Our system achieves 87. 3% accuracy, which is 17. 6% higher over the state-of-the-art method on raw image representations.

KR Conference 2018 Conference Paper

Representing Logic Programs with Ordered Disjunction Using asprin

  • Joohyung Lee
  • Zhun Yang

Logic Programs with Ordered Disjunction (LPOD) is an extension of standard answer set programs to handle preference using the high-level construct of ordered disjunction whereas asprin is a recently proposed, general, flexible, and extensible framework that provides low-level constructs for representing preference in answer set programming. We present an encoding of LPOD in the language of asprin and the implementation of LPOD called LPOD 2 ASPRIN based on the encoding. Unlike the known method that applies only to a fragment of LPOD, our translation is general, direct, and simpler. It also leads to more efficient computation of LPOD using asprin.

KR Conference 2018 Conference Paper

Weight Learning in a Probabilistic Extension of Answer Set Programs

  • Joohyung Lee
  • Yi Wang

LPMLN is a probabilistic extension of answer set programs with the weight scheme derived from that of Markov Logic. Previous work has shown how inference in LPMLN can be achieved. In this paper, we present the concept of weight learning in LPMLN and learning algorithms for LPMLN derived from those for Markov Logic. We also present a prototype implementation that uses answer set solvers for learning as well as some example domains that illustrate distinct features of LPMLN learning. Learning in LPMLN is in accordance with the stable model semantics, thereby it learns parameters for probabilistic extensions of knowledge-rich domains where answer set programming has shown to be useful but limited to the deterministic case, such as reachability analysis and reasoning about actions in dynamic domains. We also apply the method to learn the parameters for probabilistic abductive reasoning about actions.

FLAP Journal 2017 Journal Article

Fuzzy Propositional Formulas under the Stable Model Semantics.

  • Joohyung Lee
  • Yi Wang

We define a stable model semantics for fuzzy propositional formulas, which generalizes both fuzzy propositional logic and the stable model semantics of classical propositional formulas. The syntax of the language is the same as the syntax of fuzzy propositional logic, but its semantics distinguishes stable models from non-stable models. The generality of the language allows for highly configurable nonmonotonic reasoning for dynamic domains involving graded truth degrees. We show that several properties of Boolean stable models are naturally extended to this many-valued setting, and discuss how it is related to other approaches to combining fuzzy logic and the stable model semantics.

AAAI Conference 2017 Conference Paper

LPMLN, Weak Constraints, and P-log

  • Joohyung Lee
  • Zhun Yang

LPMLN is a recently introduced formalism that extends answer set programs by adopting the log-linear weight scheme of Markov Logic. This paper investigates the relationships between LPMLN and two other extensions of answer set programs: weak constraints to express a quantitative preference among answer sets, and P-log to incorporate probabilistic uncertainty. We present a translation of LPMLN into programs with weak constraints and a translation of P-log into LPMLN, which complement the existing translations in the opposite directions. The first translation allows us to compute the most probable stable models (i. e. , MAP estimates) of LPMLN programs using standard ASP solvers. This result can be extended to other formalisms, such as Markov Logic, ProbLog, and Pearl’s Causal Models, that are shown to be translatable into LPMLN. The second translation tells us how probabilistic nonmonotonicity (the ability of the reasoner to change his probabilistic model as a result of new information) of P-log can be represented in LPMLN, which yields a way to compute P-log using standard ASP solvers and MLN solvers.

KR Conference 2016 Conference Paper

Weighted Rules under the Stable Model Semantics

  • Joohyung Lee
  • Yi Wang

We introduce the concept of weighted rules under the stable model semantics following the log-linear models of Markov Logic. This provides versatile methods to overcome the deterministic nature of the stable model semantics, such as resolving inconsistencies in answer set programs, ranking stable models, associating probability to stable models, and applying statistical inference to computing weighted stable models. We also present formal comparisons with related formalisms, such as answer set programs, Markov Logic, ProbLog, and P-log.

AAAI Conference 2015 Conference Paper

Action Language BC+: Preliminary Report

  • Joseph Babb
  • Joohyung Lee

Action languages are formal models of parts of natural language that are designed to describe effects of actions. Many of these languages can be viewed as high level notations of answer set programs structured to represent transition systems. However, the form of answer set programs considered in the earlier work is quite limited in comparison with the modern Answer Set Programming (ASP) language, which allows several useful constructs for knowledge representation, such as choice rules, aggregates, and abstract constraint atoms. We propose a new action language called BC+, which closes the gap between action languages and the modern ASP language. Language BC+ is defined as a high level notation of propositional formulas under the stable model semantics. Due to the generality of the underlying language, BC+ is expressive enough to encompass many modern ASP language constructs and the best features of several other action languages, such as B, C, C+ and BC. Computational methods available in ASP solvers are readily applicable to compute BC+, which led us to implement the language by extending system CPLUS2ASP.

AAAI Conference 2015 Conference Paper

Handling Uncertainty in Answer Set Programming

  • Yi Wang
  • Joohyung Lee

We present a probabilistic extension of logic programs under the stable model semantics, inspired by the concept of Markov Logic Networks. The proposed language takes advantage of both formalisms in a single framework, allowing us to represent commonsense reasoning problems that require both logical and probabilistic reasoning in an intuitive and elaboration tolerant way.

IJCAI Conference 2013 Conference Paper

Action Language BC: Preliminary Report

  • Joohyung Lee
  • Vladimir Lifschitz
  • Fangkai Yang

The action description languages B and C have significant common core. Nevertheless, some expressive possibilities of B are difficult or impossible to simulate in C, and the other way around. The main advantage of B is that it allows the user to give Prolog-style recursive definitions, which is important in applications. On the other hand, B solves the frame problem by incorporating the commonsense law of inertia in its semantics, which makes it difficult to talk about fluents whose behavior is described by defaults other than inertia. In C and in its extension C+, the inertia assumption is expressed by axioms that the user is free to include or not to include, and other defaults can be postulated as well. This paper defines a new action description language, called BC, that combines the attractive features of B and C+. Examples of formalizing commonsense domains discussed in the paper illustrate the expressive capabilities of BC and the use of answer set solvers for the automation of reasoning about actions described in this language.

IJCAI Conference 2013 Conference Paper

Answer Set Programming Modulo Theories and Reasoning about Continuous Changes

  • Joohyung Lee
  • Yunsong Meng

Answer Set Programming Modulo Theories is a new framework of tight integration of answer set programming (ASP) and satisfiability modulo theories (SMT). Similar to the relationship between first-order logic and SMT, it is based on a recent proposal of the functional stable model semantics by fixing interpretations of background theories. Analogously to a known relationship between ASP and SAT, “tight” ASPMT programs can be translated into SMT instances. We demonstrate the usefulness of ASPMT by enhancing action language C+ to handle continuous changes as well as discrete changes. We reformulate the semantics of C+ in terms of ASPMT, and show that SMT solvers can be used to compute the language. We also show how the language can represent cumulative effects on continuous resources.

IJCAI Conference 2013 Conference Paper

Functional Stable Model Semantics and Answer Set Programming Modulo Theories

  • Michael Bartholomew
  • Joohyung Lee

Recently there has been an increasing interest in incorporating “intensional” functions in answer set programming. Intensional functions are those whose values can be described by other functions and predicates, rather than being pre-defined as in the standard answer set programming. We demonstrate that the functional stable model semantics plays an important role in the framework of “Answer Set Programming Modulo Theories (ASPMT)” —a tight integration of answer set programming and satisfiability modulo theories, under which existing integration approaches can be viewed as special cases where the role of functions is limited. We show that “tight” ASPMT programs can be translated into SMT instances, which is similar to the known relationship between ASP and SAT.

AAAI Conference 2012 Conference Paper

Reformulating Temporal Action Logics in Answer Set Programming

  • Joohyung Lee
  • Ravi Palla

Temporal Action Logics (TAL) is a class of temporal logics for reasoning about actions. We present a reformulation of TAL in Answer Set Programming (ASP), and discuss some synergies it brings. First, the reformulation provides a means to compute TAL using efficient answer set solvers. Second, TAL provides a structured high-level language for ASP (possibly with constraint solving). Third, the reformulation allows us to compute integration of TAL and ontologies using answer set solvers, and we illustrate its usefulness in the healthcare domain in the context of medical expert systems.

KR Conference 2012 Conference Paper

Stable Models of Formulas with Intensional Functions

  • Michael Bartholomew
  • Joohyung Lee

In classical logic, nonBoolean fluents, such as the location of an object and the color of a ball, can be naturally described by functions, but this is not the case with the traditional stable model semantics, where the values of functions are predefined, and nonmonotonicity of the semantics is related to minimizing the extents of predicates but has nothing to do with functions. We extend the first-order stable model semantics by Ferraris, Lee and Lifschitz to allow intensional functions. The new formalism is closely related to multivalued nonmonotonic causal logic, logic programs with intensional functions, and other extensions of logic programs with functions, while keeping similar properties as those of the first-order stable model semantics. We show how to eliminate intensional functions in favor of intensional predicates and vice versa, and use these results to encode fragments of the language in the input language of ASP solvers and CSP solvers.

IJCAI Conference 2011 Conference Paper

First-Order Extension of the FLP Stable Model Semantics via Modified Circumscription

  • Michael Bartholomew
  • Joohyung Lee
  • Yunsong Meng

We provide reformulations and generalizations of both the semantics of logic programs by Faber, Leone and Pfeifer and its extension to arbitrary propositional formulas by Truszczynski. Unlike the previous definitions, our generalizations refer neither to grounding nor to fixpoints, and apply to first-order formulas containing aggregate expressions. In the same spirit as the first-order stable model semantics proposed by Ferraris, Lee and Lifschitz, the semantics proposed here are based on syntactic transformations that are similar to circumscription. The reformulations provide useful insights into the FLP semantics and its relationship to circumscription and the first-order stable model semantics.

KR Conference 2010 Conference Paper

A Decidable Class of Groundable Formulas in the General Theory of Stable Models

  • Michael Bartholomew
  • Joohyung Lee

We present a decidable class of first-order formulas in the general theory of stable models that can be instantiated even in the presence of function constants. The notion of an argument-restricted formula presented here is a natural generalization of both the notion of an argument-restricted program and the notion of a semi-safe sentence that have been studied in different contexts. Based on this new notion, we extend the notion of safety defined by Cabalar, Pearce and Valverde to arbitrary formulas that allow function constants, and apply the result to RASPL-1 programs and programs with arbitrary aggregates, ensuring finite groundability of those programs in the presence of function constants. We also show that under a certain syntactic condition, argument-restricted formulas can be turned into argument-restricted programs.

AAAI Conference 2010 Conference Paper

Situation Calculus as Answer Set Programming

  • Joohyung Lee
  • Ravi Palla

We show how the situation calculus can be reformulated in terms of the first-order stable model semantics. A further transformation into answer set programs allows us to use an answer set solver to perform propositional reasoning about the situation calculus. We also provide an answer set programming style encoding method for Reiter’s basic action theories, which tells us how the solution to the frame problem in answer set programming is related to the solution in the situation calculus.

IJCAI Conference 2009 Conference Paper

  • Paolo Ferraris
  • Joohyung Lee
  • Vladimir Lifschitz
  • Ravi Palla

Splitting a logic program allows us to reduce the task of computing its stable models to similar tasks for smaller programs. This idea is extended here to the general theory of stable models that replaces traditional logic programs by arbitrary firstorder sentences and distinguishes between intensional and extensional predicates. We discuss two kinds of splitting: a set of intensional predicates can be split into subsets, and a formula can be split into its conjunctive terms.

IJCAI Conference 2009 Conference Paper

  • Tae-Won Kim
  • Joohyung Lee
  • Ravi Palla

Recently, Ferraris, Lee and Lifschitz presented a general definition of a stable model that is similar to the definition of circumscription, and can even be characterized in terms of circumscription. In this paper, we show the opposite direction, which is, how to turn circumscription into the general stable model semantics, and based on this, how to turn circumscriptive event calculus into answer set programs. The reformulation of the event calculus in answer set programming allows answer set solvers to be applied to event calculus reasoning, handling more expressive reasoning tasks than the current SAT-based approach. Our experiments also show clear computational advantages of the answer set programming approach.

AAAI Conference 2008 Conference Paper

A Reductive Semantics for Counting and Choice in Answer Set Programming

  • Joohyung Lee

In a recent paper, Ferraris, Lee and Lifschitz conjectured that the concept of a stable model of a first-order formula can be used to treat some answer set programming expressions as abbreviations. We follow up on that suggestion and introduce an answer set programming language that defines the meaning of counting and choice by reducing these constructs to first-order formulas. For the new language, the concept of a safe program is defined, and its semantic role is investigated. We compare the new language with the concept of a disjunctive program with aggregates introduced by Faber, Leone and Pfeifer, and discuss the possibility of implementing a fragment of the language by translating it into the input language of the answer set solver DLV. The language is also compared with cardinality constraint programs defined by Syrjänen.

KR Conference 2008 Conference Paper

On Loop Formulas with Variables

  • Joohyung Lee
  • Yunsong Meng

Recently Ferraris, Lee and Lifschitz proposed a new definition of stable models that does not refer to grounding, which applies to the syntax of arbitrary first-order sentences. We show its relation to the idea of loop formulas with variables by Chen, Lin, Wang and Zhang, and generalize their loop formulas to disjunctive programs and to arbitrary first-order sentences. We also extend the syntax of logic programs to allow explicit quantifiers, and define its semantics as a subclass of the new language of stable models by Ferraris et al. Such programs inherit from the general language the ability to handle nonmonotonic reasoning under the stable model semantics even in the absence of the unique name and the domain closure assumptions, while yielding more succinct loop formulas than the general language due to the restricted syntax. We also show certain syntactic conditions under which query answering for an extended program can be reduced to entailment checking in first-order logic, providing a way to apply first-order theorem provers to reasoning about non-Herbrand stable models.

IJCAI Conference 2007 Conference Paper

  • Paolo Ferraris
  • Joohyung Lee
  • Vladimir Lifschitz

The definition of a stable model has provided a declarative semantics for Prolog programs with negation as failure and has led to the development of answer set programming. In this paper we propose a new definition of that concept, which covers many constructs used in answer set programming (including disjunctive rules, choice rules and conditional literals) and, unlike the original definition, refers neither to grounding nor to fixpoints. Rather, it is based on a syntactic transformation, which turns a logic program into a formula of second-order logic that is similar to the formula familiar from the definition of circumscription.

AAAI Conference 2004 Conference Paper

Loop Formulas for Circumscription

  • Joohyung Lee
  • Fangzhen Lin

Clark’s completion is a simple nonmonotonic formalism and a special case of many nonmonotonic logics. Recently there has been work on extending completion with “loop formulas” so that general cases of nonmonotonic logics such as logic programs (under the answer set semantics) and McCain–Turner causal logic can be characterized by propositional logic in the form of “completion + loop formulas”. In this paper, we show that the idea is applicable to McCarthy’s circumscription in the propositional case. We also show how to embed propositional circumscription in logic programs and in causal logic, inspired by the uniform characterization of “completion + loop formulas”.

IJCAI Conference 2003 Conference Paper

Describing Additive Fluents in Action Language C+

  • Joohyung Lee
  • Vladimir Lifischitz

An additive fluent is a fluent with numerical values such that the effect of several concurrently executed actions on it can be computed by adding the effects of the individual actions. We propose a method for describing effects of actions on additive fluents in the declarative language An implementation of this language, called the Causal Calculator, can be used for the automation of examples of commonsense reasoning involving additive fluents.