We are presenting an original narrowing-based proof search method for
inductive theorems. It has the specificity to be grounded on deduction modulo
and to rely on
narrowing to provide both induction variables and instantiation
schemes. It also yields a direct translation
from a successful proof search derivation to a proof in the sequent
calculus. The method is shown to be correct and refutationally
complete in a proof theoretical way.
We are extending this first approach to equational rewrite theories given by
a rewrite system R and a set E of equalities.
Whenever the equational rewrite system (R,E) has good properties of
termination, sufficient
completeness, and whenever E is constructor preserving, narrowing at
defined-innermost positions is performed with unifiers which are constructor
substitutions. This is especially interesting for associative and
associative-commutative theories for which the general proof search
system is refined.
Keywords: deduction modulo, sequent calculus modulo, induction, Noetherian
induction,
induction by rewriting, equational reasoning, term rewriting, equational
rewriting
equational narrowing.