A hierarchy of propositional Horn formulas

Research output: Contribution to journalArticlepeer-review

Abstract

A hierarchy of propositional Horn formulas is introduced. The levels σHk and ∏Hk of the hierarchy are defined by way of the number of alternations between players in a certain game related to the satisfiability of Horn formulas. The satisfiability problems for formulas from a given level of the hierarchy are shown to be complete in NSPACE(log n). A certain relationship between the hierarchy and the bounded-depth circuits is exhibited. Using it we show that for some σHk and ∏Hk formulas the equivalent formulas in the lower levels of the hierarchy must be exponentially longer.

Original languageEnglish (US)
Pages (from-to)113-119
Number of pages7
JournalTheoretical Computer Science
Volume68
Issue number1
DOIs
StatePublished - Oct 16 1989
Externally publishedYes

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)

Fingerprint Dive into the research topics of 'A hierarchy of propositional Horn formulas'. Together they form a unique fingerprint.

Cite this