A New Pebble Game that Characterizes Parallel Complexity Classes

Abstract

A new two-person pebble game that models parallel computations is defined. This game extends the two-person pebble game defined by Dymond and Tompa [J. Comput. System Sci., 30 (1985), pp. 149–161] and is used to characterize two natural parallel complexity classes, namely LOGCFL and ${\text{AC}}^1 $. The characterizations show a fundamental way in which the computations in these two classes differ. This game model also unifies the proofs of some well-known results of complexity theory.