Luis Moniz PEREIRA
Universidade Nova de Lisboa
Revised Stable Models -
a new semantics for logic programs.
This paper introduces an original 2-valued semantics for Normal Logic
Programs (NLP), important on its own. Nevertheless, its name draws
attention to that it is inspired by and generalizes Stable Model
semantics (SM). The definitional distinction consists in the revision
of one feature of SM, namely its treatment of odd loops over default
negation. This single revised aspect, addressed by means of a
Reductio ad Absurdum approach, affords us a fruitful
cornucopia of consequences, namely regarding existence, relevance and
top-down querying, cumulativity, and implementation.
The paper motivates and then defines the Revised Stable Models
semantics (rSM), justifying the definition and providing examples. It
also presents two rSM semantics preserving program transformations
into NLP without odd loops. Properties of rSM are given and contrasted
with those of SM. Implementation is examined, and extensions of rSM
are given with regard to explicit negation, `not's in heads, and
contradiction removal. Conclusions, further work, as well as potential
use, terminate the paper.
Logic Program semantics, Stable Models, Reductio ad Absurdum.
Download: Now are available the
slide show and more
examples about rSM.
Here (follow the "Courses and talks" link) are availables the slides and the digital recording of the talk.