Tarik Hadzic

ECAI Conference 2010 Conference Paper

Knowledge Compilation for Itemset Mining

• Hadrien Cambazard
• Tarik Hadzic
• Barry O'Sullivan

We present a novel approach to itemset mining whereby the set of all itemsets are compiled into a compact form, closely related to binary decision diagrams. While there were previous attempts to utilize decision diagrams for storing the set of frequent itemsets this is the first approach that does not rely on backtrack search to generate such a set. Our empirical evaluation demonstrates that our approach is complementary to current approaches.

ECAI Conference 2008 Conference Paper

A BDD Approach to the Feature Subscription Problem

• Tarik Hadzic
• David Lesaint
• Deepak Mehta 0001
• Barry O'Sullivan
• Luis Quesada 0001
• Nic Wilson

Modern feature-rich telecommunications services offer significant opportunities to human users. To make these services more usable, facilitating personalisation is very important since it enhances the users' experience considerably. However, regardless how service providers organise their catalogues of features, they cannot achieve complete configurability due to the existence of feature interactions. Distributed Feature Composition (DFC) provides a comprehensive methodology, underpinned by a formal architecture model to address this issue. In this paper we present an approach based on using Binary Decision Diagrams (BDD) to find optimal reconfigurations of features when a user's preferences violate the technical constraints defined by a set of DFC rules. In particular, we propose hybridizing constraint programming and standard BDD compilation techniques in order to scale the construction of a BDD for larger size catalogues. Our approach outperforms the standard BDD techniques by reducing the memory requirements by as much as five orders-of-magnitude and compiles the catalogues for which the standard techniques ran out of memory.

IJCAI Conference 2007 Conference Paper

• Tarik Hadzic
• Andrzej Wasowski
• Henrik Reif Andersen

Recovering from power outages is an essential task in distribution of electricity. Our industrial partner postulates that the recovery should be interactive rather than automatic: supporting the operator by preventing choices that destabilize the network.

AAAI Conference 2006 Conference Paper

A BDD-Based Polytime Algorithm for Cost-Bounded Interactive Configuration

• Tarik Hadzic

Interactive configurators are decision support systems assisting users in selecting values for parameters that respect given constraints. The underlying knowledge can be conveniently formulated as a Constraint Satisfaction Problem where the constraints are propositional formulas. The problem of interactive configuration was originally inspired by the product configuration problem with the emergence of the masscustomization paradigm in product manufacturing, but has also been applied to other tasks requiring user interaction, such as specifying services or setting up complex equipment. The user-friendly requirements of complete, backtrack-free and real-time interaction makes the problem computationally challenging. Therefore, it is beneficial to compile the configuration constraints into a tractable representation such as Binary Decision Diagrams (BDD) (Bryant 1986) to support efficient user interaction. The compilation deals with the NPhardness such that the online interaction is in polynomial time in the size of the BDD. In this paper we address the problem of extending configurators so that a user can interactively limit configuration choices based on a maximum cost (such as price or weight of a product) of any valid configuration, in a complete, backtrack-free and real-time manner. The current BDD compilation approach is not adequate for this purpose, since adding the total cost information to the constraints description can dramatically increase the size of the compiled BDD. We show how to extend this compilation approach to solve the problem while keeping the polynomial time guarantees.