Fairy chess composition

# 57th WCCC: composing tournaments

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Kenneth Solja
August 11, 2014 17:03

Can you give some examples? I haven’t noticed any bugs ..

seetharaman
August 11, 2014 19:13

Ex.1.
White : Kf8 Qg1 Black: Kh8, Be5 #1. Popeye gives no solution ignoring 1. Qg8#. With Be5 moved to e4. Popeye gives single solution 1. Qg8#, but ignores 1.Qg7# !
Ex.2
white Pb2 Kc8 black Ka8 Ra1b1 #1 Popeye correctly gives 1.b2-a2 # If you replace Ra1 by black queen, Popeye gives ‘no solution’ even though the black queen cannot even now defend the mate (the queen cannot move as it has only pawn move after the available mate 1.b2-a2#).

dupont
August 11, 2014 20:11

In example 1, Qg8+ is not checkmate because of the parry 1…Bg7+ (and now the only legal move is 2.Ke8).

seetharaman
August 11, 2014 21:06

You are right. I am sorry! 1.Qg8+ is not mate with black bishop on e5. I missed the point of the defence 1…Bg7. But with black bishop on e4 why is 1.Qg7# not mate? Am I missing anything?

dupont
August 11, 2014 22:00

You’re right, 1.Qg7# is checkmate with bBe4. This clearly illustrates that Popeye is bugy concerning BtB. WinChloe seems safe, although it doesn’t respect the rule concerning pawns on their first row – one should add the condition “Un Pion est impuissant sur sa première rangée”.

seetharaman
August 12, 2014 21:38

Example 3: This is very interesting !!
white Pb2 Ke5 black Qh1 Ka8 Ra6a7 H#3.
One of the solutions given by Popeye is:
1.Qh1-b1 b2-b8=Q + 2.Ra7-b7 Qb8-c8 + 3.Rb7-b8 Qc8*a6 #
Obviously 2.Rb7 does not defend the check and is illegal !

Dominique Forlot
August 13, 2014 16:23

Besides, for the same “example 3”: Popeye ignores some solutions as:

1.Qh1-b1 b2-c3 2.Qb1-c1 c3-c7 3.2.Qc1-h1 c7-c8=Q #

with a nice switchback of the Queen!

Dominique Forlot
August 13, 2014 17:19

1.Qh1-b1 b2-c2 2.Qb1-c1 c2-c7 3.Qc1-h1 c7-c8=Q #

Dominique Forlot
August 13, 2014 16:52

another strange effect !
in the example 4 ( = example 3 with two knights instead of two Rooks )

white Pb2 Ke5
black Qh1 Sa7 Sa6 Ka8

Popeye find this solution ( with a dual )

1.Qh1-e4 + Ke5-a5 2.Qe4-b1 Ka5*a6 3.Sa7-b5 b2-h8=Q #

but ignore the rook promotion, also correct:

1.Qh1-e4 + Ke5-a5 2.Qe4-b1 Ka5*a6 3.Sa7-b5 b2-h8=R #
Popeye seems to consider 4.Qb1-h7?! like a defense ( as if it was just a bishop, not a queen )

Joost de Heer
August 14, 2014 21:01

Popeye 4.68 available at http://sanguis.xs4all.nl/popeye (only 32-bit version), which has fixed these errors, as far as I can see.

dupont
August 15, 2014 05:06

It seems there are still errors with proof games (or a=>b problems).

Kenneth Solja
August 15, 2014 19:12

It seems that all errors in Popeye are connected with Queen, at least I have got that impression ..

Thomas Maeder
August 17, 2014 21:30

> It seems that all errors in Popeye are connected with Queen, at least I have got that impression ..

This is my impression as well. The reason is (as almost always in these cases) an optimisation: in orthodox chess and many fairy conditions it isn’t necessary to test for observations by queens in a separate step; Popeye rather follows bishop and rook lines and tests if there is a bishop or queen resp. rook or queen lurking.

This optimisation has to be turned off in FaceToFace and related conditions.

Popeye 4.69 does this; it correctly solves all the examples given above.

seetharaman
August 18, 2014 08:45