Two-Variable Logic on Words with Data

M. Bojanczyk, A. Muscholl, T. Schwentick, Luc Segoufin, C. David
21st Annual IEEE Symposium on Logic in Computer Science (LICS'06)  
In a data word each position carries a label from a finite alphabet and a data value from some infinite domain. These models have been already considered in the realm of semistructured data, timed automata and extended temporal logics. It is shown that satisfiability for the two-variable first-order logic FO 2 (∼, <, +1) is decidable over finite and over infinite data words, where ∼ is a binary predicate testing the data value equality and +1,< are the usual successor and order predicates. The
more » ... omplexity of the problem is at least as hard as Petri net reachability. Several extensions of the logic are considered, some remain decidable while some are undecidable.
doi:10.1109/lics.2006.51 dblp:conf/lics/BojanczykMSSD06 fatcat:2wjyl5jlxngrxfuhecjhfta6tm