East-West Challenge: Results of Competition 3

Legend:
_______

Entry           is a codeword used by us for scoring purposes
Coverage        is a pair of numbers E/W  denoting  number  of  East/West  trains
		covered by the theories for each of the 5 subtasks
Size            is the complexity score of the theories submitted, as  calculated
                by Ashwin Srinivasan's Prolog program (complex.pl)
Contestant      is the name of the contestant


Notes:
______

1. Winner decided on the basis of lowest total complexity score  for
   the five subtasks.

2. In the note "UPDATE ON INDUCTIVE LEARNING COMPETITIONS" issued by
   us  on  August 3 1994, we described necessary changes to the file
   100trains.pl used to score this competition. All entries received
   before   August   3  were  scored  using  the  older  version  of
   of 100trains.pl. We believe that this change may  not  have  been
   noticed by John Roycroft. His entry royc appears to be consistent
   with the original set of 100 trains. While our rules preclude him
   from  winning Competition 3, we nevertheless include his score in
   the tabulations below.



Winner:
_______

                Bernhard Pfahringer (Entry pfahr)
                Austrian Research Institute for
                Artificial Intelligence
                Schottengasse 3
                A-1010 Vienna, Austria
		bernhard@ai.univie.ac.at



Comments:
_________


Clearly a competition for the purists, the  lack  of  a  material
reward  does not appeared to have deterred the 6 entrants. Unfor-
tunately, of these, only 3 entries complied with the rules of the
competition.   As  in  Competition 1, Bernhard Pfahringer's inex-
haustible program has delivered the goods. To him and his machine
assistant then, the Glory, and  the  associated  title  of  Train
Spotter Extraordinaire.



Details:
________



Entry	Coverage	Size	Contestant 
_____	________	____	__________


pfahr	5/0		15	Bernhard Pfahringer
	5/0		16
	5/0		15
	5/0		14
	5/0		13	
			--
			74	

	
dm2	5/0		26	Donald Michie
	0/5		15	(Westbound rule)
	5/0		29
	0/5		22	(Westbound rule)
	0/5		22	(Westbound rule)
			__
			114


royc	5/0		24	John Roycroft
	0/5		21	(Westbound rule)
	5/0		29
	0/5		17	(Westbound rule)
	5/0		31
			--
			122


mli	5/0		18	Mark Maloof
	5/0		56
	5/0		23
	5/0		31
	5/0		30
			--
			158

	--------------Below this are inconsistent------------

aqdt	5/0		16	Ibrahim F Imam
	5/1		17	has_load(Car,N) wrongly interp as exactly N?
	5/0		19
	0/5		17	Westbound rule
	5/0		16
			__
			85

turney	5/0		18	Peter D Turney
	0/2		15	assumes generative infront/3
	0/5		16	Westbound rule
	5/0		17
	0/5		16	Westbound rule
			__
			82



Prolog encoding of winning entry (pfahr)
________________________________________

% Subtask 1:
% Size = 15
eastbound([A|B]) :-
        (   rectangle(A),
            closed(A)
        ;   short(A),
            not(eastbound(B))
        ).

% Subtask 2:
% Size = 16
eastbound(A) :-
        (   not(has_load1(A,triangle))
        ;   has_load1(A, rectangle),
            has_car(A, B),
            u_shaped(B)
        ).

% Subtask 3:
% Size = 15
eastbound([_|A]) :-
        (   not(has_load1(A,rectangle))
        ;   has_car(A, B),
            bucket(B)
        ).

% Subtask 4:
% Size = 14
eastbound([A|B]) :-
        short(A),
        not(double(A)),
        not(has_load1(B,hexagon)).

% Subtask 5:
% Size = 13
eastbound([A|B]) :-
        rectangle(A),
        (   len1(B, 2)
        ;   eastbound(B)
        ).