• Publications
  • Influence
Beyond Hypertree Width: Decomposition Methods Without Decompositions
TLDR
This paper engages in a mathematical investigation of generalized hypertree width, a structural measure that has up to recently eluded study, and obtains a number of computational results, including a simple proof of the tractability of CSP instances having bounded generalizedhypertree width. Expand
Causal graphs and structurally restricted planning
TLDR
This work systematically study the complexity of planning restricted by the causal graph, and gives a complete classification theorem on causal graphs, showing that a set of graphs is either polynomial-time tractable, or is not polynomially tractable unless an established complexity-theoretic assumption fails. Expand
Meditations on Quantified Constraint Satisfaction
  • Hubie Chen
  • Mathematics, Computer Science
  • Logic and Program Semantics
  • 30 January 2012
TLDR
A viewpoint on the research program of understanding the complexity of the problems QCSP( B ) on finite structures is offered and a group of conjectures are proposed and discussed. Expand
A Model for Generating Random Quantified Boolean Formulas
TLDR
This work defines and study a general model for generating random QBF instances, and exhibits experimental results showing that the model bears certain desirable similarities to the random SAT model, as well as a number of theoretical results concerning the model. Expand
Proof Complexity Modulo the Polynomial Hierarchy: Understanding Alternation as a Source of Hardness
  • Hubie Chen
  • Mathematics, Computer Science
  • TOCT
  • 20 October 2014
TLDR
This work presents and studies a framework in which one can present alternation-based lower bounds on proof length in proof systems for quantified Boolean formulas and introduces a proof system ensemble called relaxing QU-res that is based on the established proof system QU-resolution. Expand
The complexity of constraint satisfaction games and QCSP
TLDR
The quantified constraint satisfaction framework is used to study how the complexity of deciding such a game depends on the parameter set of allowed predicates, and it is shown that the complexity is determined by the surjective polymorphisms of the constraint predicates. Expand
Quantified Constraint Satisfaction and Bounded Treewidth
TLDR
A QCSP tractability result arising from variable-based restrictions is presented by giving a polynomial time algorithm for certain classes of QCSP instances having bounded treewidth. Expand
The Complexity of Quantified Constraint Satisfaction: Collapsibility, Sink Algebras, and the Three-Element Case
  • Hubie Chen
  • Computer Science, Mathematics
  • SIAM J. Comput.
  • 24 July 2006
The constraint satisfaction probem (CSP) is a well-acknowledged framework in which many combinatorial search problems can be naturally formulated. The CSP may be viewed as the problem of deciding theExpand
A rendezvous of logic, complexity, and algebra
  • Hubie Chen
  • Mathematics, Computer Science
  • SIGA
  • 1 December 2006
I am always looking for contributions. If you have any suggestion concerning the content of the Logic Column, or if you would like to contribute by writing a column yourself, feel free to get inExpand
Asking the Metaquestions in Constraint Tractability
TLDR
This article systematically studies—for various classes of polymorphisms—the computational complexity of deciding whether or not a given structure ℍ admits a polymorphism from the class, and proves the NP-completeness of deciding a condition conjectured to characterize the tractable problems CSP(ℍ). Expand
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