This paper studies compositional semantics of nonmonotonic logic programs.
We suppose the answer set semantics of extended disjunctive programs
and consider the following problem.
Given two programs P1 and P2,
which have the sets of answer sets AS(P1) and AS(P2), respectively;
find a program Q which has answer sets as minimal sets S U T
for S from AS(P1) and T from AS(P2).
The program Q combines answer sets of P1 and P2, and
provides a compositional semantics of two programs.
Such program composition has application to coordinating
knowledge bases in multi-agent environments.
We provide methods for computing program composition and
discuss their properties.
Keywords: nonmonotonic logic programming, answer sets, program composition.