Title
A second-order system for polytime reasoning based on Grädel's theorem
Abstract
We introduce a second-order system V1-Horn of bounded arithmetic formalizing polynomial-time reasoning, based on Grädel's (Theoret. Comput. Sci. 101 (1992) 35) second-order Horn characterization of P. Our system has comprehension over P predicates (defined by Grädel's second-order Horn formulas), and only finitely many function symbols. Other systems of polynomial-time reasoning either allow induction on NP predicates (such as Buss's S21 or the second-order V11), and hence are more powerful than our system (assuming the polynomial hierarchy does not collapse), or use Cobham's theorem to introduce function symbols for all polynomial-time functions (such as Cook's PV and Zambella's P-def). We prove that our system is equivalent to QPV and Zambella's P-def. Using our techniques, we also show that V1-Horn is finitely axiomatizable, and, as a corollary, that the class of ∀Σ1b consequences of S21 is finitely axiomatizable as well, thus answering an open question.
Year
DOI
Venue
2003
10.1016/S0168-0072(03)00056-3
Annals of Pure and Applied Logic
Keywords
Field
DocType
03F35,68Q15,68Q19
Polynomial hierarchy,Discrete mathematics,Bounded arithmetic,Algebra,Second-order logic,Predicate (grammar),Corollary,Mathematics
Journal
Volume
Issue
ISSN
124
1
0168-0072
Citations 
PageRank 
References 
9
0.76
8
Authors
2
Name
Order
Citations
PageRank
Stephen Cook148642433.99
Antonina Kolokolova25010.09