Homomorphisms of conjunctive normal forms
نویسندگان
چکیده
منابع مشابه
Homomorphisms of conjunctive normal forms
We study homomorphisms of propositional formulas in CNF generalizing symmetries considered by Krishnamurthy. If φ : H → F is a homomorphism, then unsatisfiability of H implies unsatisfiability of F . Homomorphisms from F to a subset F ′ of F (endomorphisms) are of special interest, since in such case F and F ′ are satisfiability-equivalent. We show that smallest subsets F ′ of a formula F for w...
متن کاملModel-based Algorithm for Belief Revisions between Normal Conjunctive Forms
We consider a knowledge base (KB) K and a new information φ, both expressed in conjunctive form (CF), and present here, a novel, deterministic and correct algorithm for belief revision of φ in K. We denote our revision operator as: K′ = K ◦ φ. We introduce a novel logical binary operator Ind between two conjunctive forms, such that Ind(φ,K) generates also a conjunctive form. The operator Ind(φ,...
متن کاملGeneralizing Refinement Operators to Learn Prenex Conjunctive Normal Forms
Inductive Logic Programming considers almost exclusively universally quantied theories. To add expressiveness, prenex conjunctive normal forms (PCNF) with existential variables should also be considered. ILP mostly uses learning with refinement operators. To extend refinement operators to PCNF, we should first do so with substitutions. However, applying a classic substitution to a PCNF with exi...
متن کاملOn Variables with Few Occurrences in Conjunctive Normal Forms
We consider the question of the existence of variables with few occurrences in boolean conjunctive normal forms (clause-sets). Let μvd(F ) for a clause-set F denote the minimal variable-degree, the minimum of the number of occurrences of variables. Our main result is an upper bound μvd(F ) ≤ nM(σ(F )) ≤ σ(F ) + 1 + log 2 (σ(F )) for lean clause-sets F in dependency on the surplus σ(F ). Lean cl...
متن کاملBounds for variables with few occurrences in conjunctive normal forms
We investigate connections between SAT (the propositional satisfiability problem) and combinatorics, around the minimum degree of variables in various forms of redundancy-free boolean conjunctive normal forms (clause-sets). Let μvd(F ) ∈ N for a clause-set F denote the minimum variable-degree, the minimum of the number of occurrences of a variable. A central result is the upper bound σ(F ) + 1 ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2003
ISSN: 0166-218X
DOI: 10.1016/s0166-218x(02)00411-0