






          East-West Challenge: Results of Competition 1

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 theory
Size		is the complexity score of the theory submitted, as calculated by
		Ashwin Srinivasan's Prolog program (complex.pl)
Contestant	is the name of the contestant

Notes:
______

1. Entry names prefixed by "comput" were  entries  received  by  the
   British  magazine  "Computing",  in  response  to Donald Michie's
   article published on August 4.

2. Multiple entries by the same contestant are suffixed by a  number
   to indicate entry number.

3. Winner is decided on the basis of lowest complexity score.


Winner:
_______
		Bernhard Pfahringer (Entry pfahr2)
		Austrian Research Institute for
		Artificial Intelligence
		Schottengasse 3
		A-1010 Vienna, Austria
		bernhard@ai.univie.ac.at

Comments:
_________

While it is still unclear whether Eastbound planes did or did not
have  a Legless Russian President, there is no doubt that Bernard
Pfahringer's extremely compact rule (score 16) does  the  job  of
spotting trains headed in that direction. His gripping account of
The Hunt can be found in the file pfahr.txt.


Of the three competitions announced, Competition 1 proved  to  be
the  most  popular  with 63 serious entries. Competitions 2 and 3
had 6 and 7 entries respectively.  Only 18 of the   63    entries
were    via   the  Internet    call,    the    remainder    being
responses  to Donald Michie's article in  the  British   computer
magazine  "Computing".  Despite  being outnumbered by almost 3 to
1, the Internet entries fared well, with 13 doing better than the
best   from  "Computing" readers.  With  the  Internet  responses
coming largely from the International Machine Learning community,
the  scoreline  appears to stand at Machines 1, Humans 0.


Some other statistics. A frequency histogram of the sizes of some
of the more compact theories known to us is as follows (not drawn
to scale):

Number of
theories
    ^
    |
    |
    |                           9
    |                           |
    |                           |
    |                           |
    |       5      5            |
    |       |      |        4   |
    |       |      |        |   |              3
    |  2    |  2   |        |   |     2  2     |           2
    |  |    |  |   |  1  1  |   |  1  |  |  1  |       1   |  1
    |  |    |  |   |  |  |  |   |  |  |  |  |  |       |   |  |
    |--|----|--|---|--|--|--|---|--|--|--|--|--|-------|---|--|---> Theory
      16   19 20  22 23 24 25  27 28 29 30 31 32      38  42 43     size
    
		         ^
		         |___ first entry from a "Computing" reader


The alert reader would have spotted  an  anomaly.  The  histogram
shows lists 2 theories at size 16. One of these is the Pfahringer
entry.  The other is an effort by Donald Michie and  David  Page,
inspired   by  the  winning  entry. While obviously ineligible to
compete here, the theory nevertheless qualifies as a Theory Known
To   Us.   There are two other such mysterious theories: Theory X
(size 19), which acted as pace-setter for much of  the  race  and
an  early effort by Donald Michie (size 29).


In the interim, we wait to see if machine-learning programs  will
some  day  have the numerical apparatus to produce something like
the following effort by Donald Macleod:

	Let A = Total number of sides in the 3rd last car
	Let B = 1 if 3rd last car is single walled, 0 otherwise
	A = B = 0 if the train has less than 3 cars

	If A*B is a triangular number (i.e. 1,3,6,10...)
	then Eastbound
	else Westbound


We reserve judgement about entries like:

	Eastbound trains have the engine at the front, but
	Westbound trains have the engine at the back

More details on the "brains-only" creations from "Computing"
readers is in the file michie.txt


Details:
________


Entry		Coverage	Size	Contestant
_____		________	____	__________

pfahr2		10/0		16	Bernhard Pfahringer
inglis		10/0		19	Stuart Inglis
pfahr1		10/0		19	Bernhard Pfahringer
turney		10/0		19	Peter D Turney
weka		10/0		19	WEKA ML Project
aqdt1		10/0		20	Ibrahim F Imam
aqdt2		10/0		20	Ryszard S Michalski

	-----------Bottom quartile ends here----------

akay		10/0		22	Andrew Kay
aq17hci		10/0		22	Janusz Wnek
gamb1		10/0		22	Dragan Gamberger
mli		10/0		22	Mark Maloof
quin		10/0		22	Ross Quinlan
rudy		10/0		23	Rudy Setiono
comput2		10/0		24	Richard Lawrence
comput1		10/0		25	Nicholas Knowles
comput9		10/0		25	T M Bradshaw
comput10	10/0		25	Alan D Cox
comput11	10/0		25	Tony Yule
pfahr3		10/0		27	Bernhard Pfahringer
comput13	10/0		27	Stephane Deom
comput14	10/0		27	Stephane Deom
comput15	10/0		27	R M Yaxley
comput18	10/0		27	Jane Flanders
comput22	10/0		27	Ian Thirkettle
comput24	10/0		27	P Smith
comput25	10/0		27	D P Sayers
comput27	10/0		27	Nick Henfry
comput12	10/0		28	John Brown
comput28	10/0		29	Nick Henfry
comput3		10/0		30	Peter Guy
comput21	10/0		30	A R Archer
vogt		10/0		31	Chris Vogt
comput6		10/0		32	Andrew Davies
comput8		10/0		32	Sue Wood
comput23	10/0		32	David Nelson
mcdon		10/0		38	mcdonald@edu.kestrel
comput4		10/0		42	Bernard Lucas
gamb2		10/0		42	Dragan Gamberger
comput46	0/10		43	R D Scott Westbound rule

	-----------Too complex----------

hart		_		_	hart@uk.ac.ox.vax
comput16	_		_	G E Tyack
comput20	_		_	Demetrios Papacharalambous
comput5		_		_	Judy BroadwaY
comput29	_		_	S Roy
comput30	_		_	Melvyn Maltz
comput31	_		_	Mark Henry
comput32	_		_	Kevin Ferriday
comput33	_		_	J Gibbons
comput34	_		_	Donald Mcleod
comput35	_		_	R Millar
comput37	_		_	M White
comput38	_		_	Gianni Pischedda
comput39	_		_	Chris Derry
comput40	_		_	Hans Wrang
comput41	_		_	Peter Young
comput42	_		_	Chris Bergman
comput43	_		_	Peter Young
comput44	_		_	Tim Binney
comput45	_		_	Ian Barker
comput47	_		_	Frank Smith

	-----------Inconsistent----------

comput17	_		_	Jane Moch just fits 10 trains?
comput19	_		_	Demetrios Papacharalambous
comput26	_		_	Simon Towner
comput29	_		_	Marcus Sean Rebel
comput36	_		_	Dennis Collie


Prolog encoding of theories in bottom quartile
______________________________________________

% pfahr2, Bernhard Pfahringer
% Size  = 16
eastbound([Car|Cars]) :-
        (closed(Car);has_load1(Cars, triangle)),
        (short(Car);eastbound(Cars)).

% mpage, Michie-Page effort inspired by pfahr2
% Size = 16
eastbound([Car|Cars]):-
        short(Car),
        (closed(Car);has_load1(Cars,triangle));
        eastbound(Cars).

% pfahr1, Bernhard Pfahringer
% inglis, Stuart Inglis
% weka, WEKA ML Project
% Size = 19
eastbound([Car1,Car2,Car3|_]) :-
        has_load0(Car1,_),
        has_load0(Car3,Load),
        not(has_load0(Car2,Load)).

% turney, Peter Turney
% Size = 19
turney(T) :-
        has_car(T, C1),
        (( short(C1), closed(C1)) ;
        (len1(T,4), u_shaped(C1), has_load1(T, circle))).

% x, Theory X
% Size = 19
eastbound([Car|Cars]):-
        (short(Car), closed(Car));
        (has_load0(Car,circle), has_load1(Cars,triangle));
        eastbound(Cars).

% aqdt1, Ibrahim F Imam
% Size = 20
eastbound([Car1,Car2,Car3|_])  :-
	has_load0(Car3,triangle);
	(rectangle(Car1),
	short(Car2),
	not(double(Car3))).

% aqdt2, Ryszard S Michalski
% Size = 20
eastbound([Car1,Car2,Car3|_])  :-
	has_load0(Car3,triangle);
	rectangle(Car1),
	(closed(Car3);
	hexagon(Car2)).

