The 14th Prolog Programming Contest Bart Demoen and Phuong-Lan Nguyen K.U.Leuven Belgium Editor: Enrico Pontelli (The announcement of the results of the 14-th Prolog Programming Contest at the banquet of ICLP'07 in Porto.) First my thanks to the people who helped making this 14th Prolog Programming Contest a success: Illka Niemela and Veronica Dahl for a superb slot in the program, Fernando Silva for the required accomodation, Gopal Gupta for sponsoring the contest financially through his company Logical Software Solutions (logicalsoft.net) and Phuong-Lan Nguyen for cooking up the questions together with me. Last year, at ICLP'06 in Seattle, the announcement of the winners of this contest turned into a banquet speech, because Peter Stuckey - who was supposed to deliver it - did not show up. Since then, I always carry a spare banquet speech with me, just in case, but luckily, Peter is here, and he will deliver a hell of a speech later on. Let me first explain once more how this contest is conducted: we lock up in a room about 10 teams of 2-3 people; each team gets the right to use one latop, one set of questions and two hours to solve them. Team members are meant to cooperate. This might not seem so easy when the team members have never met before, like the team with Alexei Mozorow, Neng-Fa Zhou and Paul Tarau. But at least they were very civilized with each other: I heard them decide on a round-robin schedule for using the keyboard and when it was the next person's turn, I heard them say polite things like "if you are almost done, please continue for a while". On the other hand, the team with Peter Stuckey, Lee Naish and Kostis Sagonas - they know each other quite well - was shouting at each other: "go away from my keyboard. you bastard, how could you forget the recursive calls". There were nine teams this year: not the highest number ever, not the lowest either. Each team had exactly 3 members. Apart from the teams already mentioned, there was the Hungarian team that tried to prolongue their title for the third year. There was one Italian team with Agostino Dovier who will do ICLP'08 in Udine. One Portuguese team with a remarkable contest spirit (see later). One Vietnamese team with Jan Wielemaker. One very mixed team with Ka-Shu Wong who almost won the contest singlehandedly last year. And there were two Belgian teams. Of all the participants, 7 people had won the contest before, some even more than once. People could use any of the following Prolog (like) systems: SISCtus, SWI, B-, GNU, XSB and Yap. That is just every Prolog I got installed in time on my machine: I test the submitted solutions immediately. Yap was of course used by the Portuguese team: Yap turns out to be the fastest Prolog system to write buggy programs in. But in defense of the Portuguese team, I must say that they found the bug themselves. some 15 minutes after our test suite had already accepted their solution: they wanted to resubmit, but the rules do not favour such honesty. Talking about bugs: 31 solutions were submitted, and only 5 were wrong. That is really amazingly good. The bad submissions were anticipating Gopal's talk on co-induction: I had the definite feeling that they would have ended under his co-semantics. When a team submits its first solution (it need not be correct), its members get Belgian chocolates - that's tradition. There was one novelty this year, and it could influence the outcome of this contest in a dramatic way: some problems gave a time bonus for a good solution. The thing is this: the team solving the most problems wins, and in case of a tie, the total time for solving the problems breaks the tie. The one keyboard/team is a bottleneck and it always occupied: someone is typing ... except in the Hungarian team: their keyboard was often left alone, and the team members were actually thinking most of the time. In the past two years, this strategy worked well and they won. This year, no such luck: as the only team, they solved 3 problems, but there were 4 teams that solved 4 problems: this is unheard of. But no team solved 5 or 6. Four teams with the same amount of maximal number of solved problems: the total time had to decide on the winner, and the bonus could play its role. Let's first name the four teams: one Belgian team - with Leslie De Koninck, Peter Van Weert and Jon Sneyers (all three PhD students from Leuven !) - solved 4 problems, earned 10 bonus minutes and ended at the fourth place. The Italian team - Agostino Dovier, Alessandro Dal Palu and Elisabetta de Maria - earned 20 bonus minutes and came in third. The two remaining teams were quite a bit faster than those two: another Belgian team - Tom Schrijvers, Pieter Wuille and Paolo Pilozzi (again three students from Leuven !) - and the Australo-Greek team already named before. Without the bonus, the Belgians were minutes ahead of the OzzieGreeks. The bonus for the latter team was 20 minutes, while only 10 for the Belgians ... Still, the Belgians won with a narrow margin of 8 minutes. They are now the proud owners of a t-shirt showing Porto wine bottles and glasses, and the text: VENCEDOR of the 14th Prolog Programming Contest - congratulations. Before I quit, two more things: the book about the first 10 editions of this contest is stilll available, hardcopy from me, free download from my website. And the 15th Prolog Programming Contest will take place in Udine, Italy, at the occasion of ICLP'08. See you next year, Bart Demoen and Phuong-Lan Nguyen Pictures courtesy of Alexei Morozov