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MatPlus.Net Forum General Most illegal position :-)
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(1) Posted by Hauke Reddmann [Wednesday, Jan 29, 2020 09:22]

Most illegal position :-)

Seeing Arnos new attempt (illegal h#), I immediately noticed
the position is "even more illegal" than before. I know, a position
can only be legal or illegal. But even already 40 years ago
I made a throwaway pun for INSELSCHACH comparing Legal's Mate
(any OTB player should know) with Illegal's Mate (I'm too lazy
to look up what I put in, but it included a piece standing on
four fields at the same time :-) that collected many reasons for
an illegal position.

Thus, two fun problems for MPF:
- Most Illegal Cluster
a) A position with as many different illegality reasons as possible.
- Largest Illegal Cluster
b) A position with as many pieces needed to be removed as possible.

Doesn't have to be a "cluster" in the IC sense - and touching kings
are fatal anyway. But try to make the reasons in a) mutually
independent. b) sounds trivial - can you do better than KK+62Q?
(With fairies you could do 62 a,b-knights that all check the poor
K simultaneously, so 61 must be removed... Also, putting 64 K on the
board in b) will be punishable by trout slap :-)

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(2) Posted by Jakob Leck [Wednesday, Jan 29, 2020 20:40]

64 kings in b) was exactly what I intended until I read to the end of your post.^^
To clarify a): If one of the reasons for illegality is the fact that there could not have been a last move, can I then claim different causes of illegality based on things that must have happened in the course of a proof game leading to the diagram position even though there could not have been one?
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(3) Posted by Hauke Reddmann [Thursday, Jan 30, 2020 10:11]

Feel free to do it as in modern 2# and before court: eloquence beats logic :-)
(It's a joke task anyway...)
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(4) Posted by Ulrich Voigt [Saturday, Feb 1, 2020 18:38]


(= 32+32 )

Only seven queens can remain, two less than in KK+62Q.
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(5) Posted by Hauke Reddmann [Sunday, Feb 2, 2020 11:29]

Cool! But one of us two has miscounted in this chaos :-)
I count six: the two nonchecking black, the two nonchecking white
and two white from the same line.
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(6) Posted by Ulrich Voigt [Sunday, Feb 2, 2020 11:42]

Three from the same line - f5, f6, f7.
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(7) Posted by Hauke Reddmann [Sunday, Feb 2, 2020 12:09]

Of course. Mathematicians shouldn't try to count :-)
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MatPlus.Net Forum General Most illegal position :-)