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All reports by Author Oliver Kullmann:

TR07-055 | 22nd May 2007
Oliver Kullmann

Constraint satisfaction problems in clausal form: Autarkies and minimal unsatisfiability

Revisions: 1

We consider the next step from boolean conjunctive normal forms to
arbitrary constraint satisfaction problems (with arbitrary constraints), namely "generalised clause-sets" (or "sets of no-goods"), which allow negative literals "v <> e" for variables v and values e --- this level of generality appears to be the right level for ... more >>>

TR00-018 | 16th February 2000
Oliver Kullmann

An application of matroid theory to the SAT problem

A basic property of minimally unsatisfiable clause-sets F is that
c(F) >= n(F) + 1 holds, where c(F) is the number of clauses, and
n(F) the number of variables. Let MUSAT(k) be the class of minimally
unsatisfiable clause-sets F with c(F) <= n(F) + k.

Poly-time decision algorithms are known ... more >>>

TR99-041 | 22nd August 1999
Oliver Kullmann

Investigating a general hierarchy of polynomially decidable classes of CNF's based on short tree-like resolution proofs

Revisions: 2

A relativized hierarchy of conjunctive normal forms
is introduced, recognizable and SAT decidable in polynomial
time. The corresponding hardness parameter, the first level
of inclusion in the hierarchy, is studied in detail, admitting
several characterizations, e.g., using pebble games, the space
complexity of (relativized) tree-like ... more >>>

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