 
Summary: Robustness of PSPACEcomplete sets
A. Pavan a,1
and Fengming Wang b,1
aDepartment of Computer Science, Iowa State University.
pavan@cs.iastate.edu
bDepartment of Computer Science, Rutgers University.
fengming@cs.rutgers.edu
Abstract
We study the robustness of complete languages in PSPACE and prove that they are
robust against Pselective sparse sets. Earlier similar results are known for EXP
complete sets [3] and NPcomplete sets [7].
Key words: Computational Complexity, Complete Sets, Robustness, Pselective
Sets, PSPACE.
1 Introduction
This paper studies the robustness of complete sets which was initiated by
Sch¨oning [8]. Informally, a complete set is robust if it remains complete/hard
even after we remove a small amount of information from it. More formally, if
L is complete for a complexity class C, we say L is robust against a set S if
L  S is remains complete/hard for C.
Several results are known regarding the robustness of complete sets for classes
