Existential Second-Order Logic over Strings

d abstract) T. Eiter G. Gottlob Y. Gurevich Institut fur Informatik Institut fur Informationssysteme EECS Department Universitat Gie en Technische Universitat Wien University of Michigan D-35392 Gie en, Germany A-1040 Vienna, Austria Ann Arbor, MI 48109{2122 Existential second-order logic (ESO) and monadic second-order logic (MSO) have attracted much interest in logic and computer science. ESO is a much more expressive logic over word structures than MSO. However, little was known about the relationship between MSO and syntactic fragments of ESO. We shed light on this issue by completely characterizing this relationship for the pre x classes of ESO over strings, (i.e., nite word structures). Moreover, we determine the complexity of model checking over strings, for all ESO-pre x classes. We also give a precise characterization of those ESO-pre x classes which are equivalent to MSO over strings, and of the ESO-pre x classes which are closed under complementation on strings.

• Type: Conference
• Year: 1998
• Where: LICS
• Authors: Thomas Eiter, Georg Gottlob, Yuri Gurevich
• Keywords: Automated Reasoning, Institut Fur, LICS 1998, Monadic Second-order Logic, Second-order Logic