[jvdh]

I doubt whether this is the actual reason that Prolog was killed off. AFAIK during the 90s there was still research going on with Prolog and parallelization. However, this seems to have been killed off during the end of the 90s because of lack of results.

IMO the thing that killed Prolog is that there has never been a good way to do parallelization without having to massively rewite Prolog programs.

[larsberg]

There's still some active research in Parallel Prolog implementation. See this fabulous survey paper of the implementation approaches: http://portal.acm.org/citation.cfm?id=504083.504085 Gupta, G., Pontelli, E., Ali, K. A., Carlsson, M., and Hermenegildo, M. V. 2001. Parallel execution of prolog programs: a survey. ACM Trans. Program. Lang. Syst. 23, 4 (Jul. 2001), 472-602.

Hermenegildo, in particular, continues active research in this area and is quite visible and active in the broad programming languages community.