We study the complexity of the Subgraph Bisimulation Problem, which stands to Graph Bisimulation as Subgraph Isomorphism stands to Graph Isomorphism and we prove its NP-Completeness. Our analysis is motivated by its applications to Semistructured Databases.

We investigate the complexity of the syntactic isomorphism problem of CNF Boolean Formulas (CSFI): given two CNF Boolean formulas φ(a1, . . . , an) and φ(b1, . . . , bn) decide whether there exists a permutation of clauses, a permutation of literals and a bijection between their variables such that φ(a1, . . . , an) and φ(b1, . . . , bn) become syntactically identical. We first show that the CS...

We give a new upper bound for the Group and Quasigroup Isomorphism problems when the input structures are given explicitly by multiplication tables. We show that these problems can be computed by polynomial size nondeterministic circuits of unbounded fan-in with O(log log n) depth and O(log n) nondeterministic bits, where n is the number of group elements. This improves the existing upper bound...

The isomorphism problem for finitely generated Coxeter groups is the problem of deciding if two finite Coxeter matrices define isomorphic Coxeter groups. Coxeter [4] solved this problem for finite irreducible Coxeter groups. Recently there has been considerable interest and activity on the isomorphism problem for arbitrary finitely generated Coxeter groups. In this paper we describe a family of...

We study the complexity of testing if two given matroids are isomorphic. The problem is easily seen to be in Σ 2 . In the case of linear matroids, which are represented over polynomially growing fields, we note that the problem is unlikely to be Σ 2 -complete and is coNPhard. We show that when the rank of the matroid is bounded by a constant, linear matroid isomorphism and matroid isomorphism a...

We address the question of whether two multiplayer strategic games are equivalent and the computationalcomplexity of deciding such a property. We introduce two notions of isomorphisms, strong and weak. Each oneof those isomorphisms preserves a different structure of the game. Strong isomorphism are defined to preservethe utility functions and Nash equilibria. Weak isomorphism preser...