Reconstructing the Evolutionary History of Indo-European Languages using Answer Set Programming.
Esra Erdem, Vladimir Lifschitz, Luay Nakhleh, and Donald Ringe. PADL'03.
The evolutionary history of languages can be modeled as a tree, called a
phylogeny, where the leaves represent the extant languages, the internal
vertices represent the ancestral languages, and the edges represent the
genetic relations between the languages. Languages not only inherit
characteristics from their ancestors but also sometimes borrow them from
other languages. Such borrowings can be represented by additional non-tree
edges. This paper addresses the problem of computing a small number of
additional edges that turn a phylogeny into a "perfect phylogenetic
network". To solve this problem, we use answer set programming, which
represents a given computational problem as a logic program whose answer
sets correspond to solutions. Using the answer set solver SMODELS, with
some heuristics and optimization techniques, we have generated a few
conjectures regarding the evolution of Indo-European languages.
The talk presented a good introduction to answer-set programming.
The answer-set logic programming is more general than Prolog's
built-in Depth-First search. For one thing, the answer-set semantics
admits more logical programs (because answer-set solvers find
solutions where equivalent Prolog programs just loop). For another,
the answer-set semantics makes it very easy to keep adding
The generated conjectures have been subjected to validation by
professional linguists. Three conjectures were validated -- one of
which wasn't known before.
Posted to Logic/Declerative by Ehud Lamm on 2/17/03; 4:32:05 AM