True 3-D displays for avionics and mission crewstations
Elizabeth A. Sholler, Frederick M. Meyer, et al.
SPIE AeroSense 1997
We study here the language Datalog (≠), which is the query language obtained from Datalog by allowing equalities and inequalities in the bodies of the rules. We view Datalog (≠) as a fragment of an infinitary logic Lw and show that Lw can be characterized in terms of certain two-person pebble games. This characterization provides us with tools for investigating the expressive power of Datalog (≠). As a case study, we classify the expressibility of fixed subgraph homeomorphism queries on directed graphs. S. Fortune, J. Hopcroft, and J. Wyllie (Theoret. Comput. Sci. 10 (1980), 111-121) classified the computational complexity of these queries by establishing two dichotomies, which are proper only if P ≠ NP. Without using any complexity-theoretic assumptions, we show here that the two dichotomies are indeed proper in terms of expressibility in Datalog (≠). © 1995 by Academic Press, Inc.
Elizabeth A. Sholler, Frederick M. Meyer, et al.
SPIE AeroSense 1997
Trang H. Tran, Lam Nguyen, et al.
INFORMS 2022
Simeon Furrer, Dirk Dahlhaus
ISIT 2005
Joseph Y. Halpern, Moshe Y. Vardi
STOC 1988