As to whether Prolog is "dead" or not, it depends on your definition of "dead". Three years ago (not ten!) I made my living maintaining and developing a large application written in Prolog. That was actually an interesting experience, since one of the performance drivers was speed. As a result code was being perpetually tuned toward less non-determinism. You know what the limit is? Functional programming! At the time I did a little research looking for an FP language that was "ready for prime time" and for which the pain of the move for a large organization would have been acceptably low. Sadly, nothing came of it. I still think the application could have been profitably ported to a functional language. Recently I have been experimenting with ECLiPSe, a Constraint Logic Programming system embedded within standard Prolog. I found several of the problems in the Euler Project were perfect candidates for attack by constraint programming. Yes, I could have written solutions that implemented some sort of search strategy, but there is a legitimate question of leverage. For example, Sudoku puzzles are very naturally viewed as constraint programming problems. But why should I write my own solution when the Sudoku solver provided as a demo could solve 50 problems in 0.10 seconds! By the way, I could get a fairly good idea of the "how and why" of the problem nd its solution from the form of the demo code, and oh yes I had already written my own Sudoku solver on OCaml a year or so ago. To Jerzy's point -- I strongly believe that learning a language like Prolog is a good idea for two reasons -- first, it adds another tool to the programmer's toolkit, and second, it enlarges the programmer's view of ways to think about solving problems. -- Bill Wood