next up previous
Next: Michael Gelfond Up: Statements of the panelists Previous: Statements of the panelists

Chitta Baral

raised in his comments one more question: In most approaches, ASP solutions to a problem are represented by answer sets. While doing answer set programming, is one still interested in entailment?

His answers to questions 1.-4. are:

Ad Q1.
Although most languages/language extensions have a clean formal characteristics, we still lack of more useful building block results (like e.g. splitting sets) for proofs.

Ad Q4.
In answer set programming solutions are answer sets, while in prolog, solutions are substitutions. If we deal with lists/sets of assignments, this makes a major difference.

An interesting point is when we deal with problems in P vs problems in NP. For problems in P there are nice efficient solutions in Prolog, while in ASP we have not so much control on the search and we have to effectively indirectly guess solutions. A motivating example is List concatenation:

  conc([],L,L).
  conc([H|L1],L2,[H|L3]) :- conc(L1,L2,L3).
While in Prolog this can be done efficiently, in ASP we can represent the data structures to some extent but guess all solutions, i.e. lists in some sense.

Chitta reminded at this point Piero Bonatti's approach for finitary programs and restricted use of function symbols in this context.


next up previous
Next: Michael Gelfond Up: Statements of the panelists Previous: Statements of the panelists
Stefan Woltran 2005-08-22