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-   -   September 2017 (https://www.mersenneforum.org/showthread.php?t=22551)

R. Gerbicz 2017-08-30 14:19

September 2017
 
The new Ibm puzzle is out: [url]https://researchweb.watson.ibm.com/haifa/ponderthis/challenges/September2017.html[/url]

science_man_88 2017-08-30 22:08

quite a few restrictions as I see it.

science_man_88 2017-08-31 13:26

for anyone wondering these restrictions include:

[SPOILER] rook can't be within 2 of the king on the side being attacked, knight can't be 3 out from the king, bishop can't be 2 out from the king. [/SPOILER]

LaurV 2017-08-31 13:31

That is a nice one for hand practice! However, easy to program, and the search space is very small, only 960 positions, of each two moves (first is a pawn move), extremely small!

Most probably, skip.
(no time...:sad:)

LaurV 2017-08-31 13:37

[QUOTE=science_man_88;466751]for anyone wondering these restrictions include:

[SPOILER] rook can't be within 2 of the king on the side being attacked, knight can't be 3 out from the king, bishop can't be 2 out from the king. [/SPOILER][/QUOTE]
That is not true, about horses, see how the [URL="https://en.wikipedia.org/wiki/Chess960_starting_position"]starting positions[/URL] are chosen using dices. The only restrictions are king between rooks and opposite-color bishops. Other (concerning castling, whatever) are not of any concern, because the game will not progress so much, you mate in two. And there is no need for spoilers when you talk about what position is valid, this is assumed known by hypothesis. There are 960 positions, that's all. You do not need to reinvent this part. You only need to say how many of these 960 allow a fool mate for either black or white.

henryzz 2017-08-31 13:47

[QUOTE=LaurV;466752]That is a nice one for hand practice! However, easy to program, and the search space is very small, only 960 positions, of each two moves (first is a pawn move), extremely small!

Most probably, skip.
(no time...:sad:)[/QUOTE]

More time consuming programming than actually hard. I am thinking of doing it by hand.

science_man_88 2017-08-31 14:08

[QUOTE=LaurV;466754]That is not true, about horses, see how the [URL="https://en.wikipedia.org/wiki/Chess960_starting_position"]starting positions[/URL] are chosen using dices. The only restrictions are king between rooks and opposite-color bishops. Other (concerning castling, whatever) are not of any concern, because the game will not progress so much, you mate in two. And there is no need for spoilers when you talk about what position is valid, this is assumed known by hypothesis. There are 960 positions, that's all. You do not need to reinvent this part. You only need to say how many of these 960 allow a fool mate for either black or white.[/QUOTE]

it isn't false about the knight laurv, if you have a knight 3 out from the king on the side being attacked it can block the queens attack.

LaurV 2017-08-31 14:25

aaa.. ok, now I understood what you want to say, and I understood why you used the spoiler, you actually were trying to solve the puzzle, but I though you were talking about restrictions when you set the initial position. However, that does not affect the result, if you do it by hand it just doesn't matter, and if you do it with a program, the program is not interested in these "restrictions", it just tries brute force, all possible combinations of two moves, from which one must be a pawn move (as well it can be the first, no matter if you start with a horse, you will still need to move a pawn to allow fool mate) and exits if a fool mate is found. The search space is very small.

henryzz 2017-08-31 18:53

[QUOTE=science_man_88;466756]it isn't false about the knight laurv, if you have a knight 3 out from the king on the side being attacked it can block the queens attack.[/QUOTE]

Yes but can't white move a pawn on the first move and that knight on the second moving it out of reach.
Also, I can't see why fools mate needs to be the queen couldn't a bishop do a 2 move CM in 960

science_man_88 2017-08-31 20:25

[QUOTE=henryzz;466783]Yes but can't white move a pawn on the first move and that knight on the second moving it out of reach.
Also, I can't see why fools mate needs to be the queen couldn't a bishop do a 2 move CM in 960[/QUOTE]

consistent definitions between variants ? in theory yes a bishop could in theory if it can be placed int he correct position without wrecking what else is needed to be avoided.

LaurV 2017-09-01 05:47

[QUOTE=henryzz;466783]Yes but can't white move a pawn on the first move and that knight on the second moving it out of reach.
Also, I can't see why fools mate needs to be the queen couldn't a bishop do a 2 move CM in 960[/QUOTE]
You need to move both pawns, otherwise the second pawn blocks the mate, in most cases (except when the bishop/queen/whatever is on line 4). You still get a fool mate, but not in the minimal number of moves. In fact when you send the solution, you may need to specify like "x positions allow fool mate in 2, y positions allow fool mate in 3, z positions allow fool mate in 4", etc(up to you how high you want to go :razz:, because if they are not very specific about it, so it can be interpreted one way or the other.


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