Maximum Renamable Horn sub-CNFs
نویسنده
چکیده
The NP-hard problem of finding the largest renamable Horn sub-CNF of a given CNF is considered, and a polynomial time approximation algorithm is presented for this problem. It is shown that for cubic CNFs this algorithm has a guaranteed performance ratio of 40 67 .
منابع مشابه
On Hierarchies over the Class of SLUR Formulae
Single look-ahead unit resolution (SLUR) algorithm is a nondeterministic polynomial time algorithm which for a given input formula in a conjunctive normal form (CNF) either outputs its satisfying assignment or gives up. A CNF formula belongs to the SLUR class if no sequence of nondeterministic choices causes the SLUR algorithm to give up on it. The SLUR class is reasonably large. It is known to...
متن کاملAlgorithms for Propositional KB Approximation
One of the obstacles to the effective compilation of propositional knowledge bases (KBs) using Horn approximations, as introduced by (Selman & Kautz 1991), is the lack of computationally feasible methods for generating Horn bounds. In this paper new algorithms for generating Horn Greatest Lower Bounds (GLB) that can apply to large size KBs, are presented. The approach is extended through a more...
متن کاملOn 2-SAT and Renamable Horn
We introduce new linear time algorithms for satisfiability of binary propositional theories (2-SAT), and for recognition and satisfiability of renamable Horn theories. The algorithms are based on unit resolution, and are thus likely easier to integrate within general SAT solvers than other graph-based algorithms.
متن کاملDetecting Embedded Horn Structure in Propositional Logic
We show that the problem of nding a maximum renamable Horn problem within a propositional satis ability problem is NP hard but can be formulated as a set packing and therefore a maximum clique problem for which numerous algorithms and heuristics have been developed
متن کاملA Modular Reduction of Regular Logic to Classical Logic
In this paper we first define a reduction Æ that transforms an instance of Regular-SAT into a satisfiability equivalent instance Æ of SAT. The reduction Æ has interesting properties: (i) the size of Æ is linear in the size of , (ii) Æ transforms regular Horn formulas into Horn formulas, and (iii) Æ transforms regular 2-CNF formulas into 2-CNF formulas. Second, we describe a new satisfiability t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Discrete Applied Mathematics
دوره 96-97 شماره
صفحات -
تاریخ انتشار 1999