fjdkslagh wrote:
both kings are in check at the same time, easy
Illegal Position Contest!
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fjdkslagh wrote:
that was a mental mistake. pretend the black king was somewhere else and a bishop was there.
so this is what I was thinking:
What is the simplest form of that kind of illegal position? Here's a possibility.
Dec 14, 2023
0
#7904
Depends if it needs to be knight check or just the checking piece has nowhere to come from.
Dec 14, 2023
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#7905
#7942. No problem. Just put your board the right way up, like @n9531l1's.
#7943. Same.
I suspect you've hit on the reason the pieces were at their respective ends in the original diagrams.
White was supposed to be stalemated before that could happen, but I forgot that the bishop can move 🤦
MARattigan wrote:
Depends if it needs to be knight check or just the checking piece has nowhere to come from. (#7941)
Suppose you're given a king of each color and one extra black unit not a king, and asked to make an illegal position with non-adjacent kings. For which types of extra unit could you do it? Obviously a pawn could be put on the 8th rank, and a bishop could be put on a8 with the white king on b7. But what if the extra unit is a queen, rook, or knight?
Dec 14, 2023
0
#7910
n9531l1 wrote:
MARattigan wrote:
Depends if it needs to be knight check or just the checking piece has nowhere to come from. (#7941)
Er, yes. Maybe I should stop posting till next year.
@Leither123 re #7948. Yes again. See comment above (maybe definitely).
Just to be inconsistent:
MARattigan wrote:
@Leither123 re #7948. Yes again. See comment above (maybe definitely).
Well, I can certainly respond to n95's comment. Was it the comment you meant for me to read?
Besides a pawn or bishop, the only type of unit that can be used is a rook.
Dec 14, 2023
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#7912
No, I just meant maybe I should stop posting for a while.
Brain's preoccupied with thinking about what I need to do before Christmas and New Year. (Not doing anything, you understand; just thinking about it.)
Dec 14, 2023
0
#7913
n9531l1 wrote:
Suppose you're given a king of each color and one extra black unit not a king, and asked to make an illegal position with non-adjacent kings. For which types of extra unit could you do it? Obviously a pawn could be put on the 8th rank, and a bishop could be put on a8 with the white king on b7. But what if the extra unit is a queen, rook, or knight?
Pawn and bishop have other possibilities of course.
I should do the same; I keep making simple mistakes.
Dec 14, 2023
0
#7915
These are also illegal under FIDE competition rules.
Ply count under the 75 move rule = 1
Ply count under the 75 move rule = 141
MARattigan wrote:
These are also illegal under FIDE competition rules.
Ply count under the 75 move rule = 1
Ply count under the 75 move rule = 141
How does the FIDE rule read that makes this an illegal position?
Dec 15, 2023
0
#7917
That has a ply count of 8 under the 75 move rule. It's legal. Can you get there legally under FIDE competition rules with a ply count of 141 under the 75 move rule?
(You can get there in the the chess.com GUI, but that's a different matter; it doesn't necessarily terminate the game in accordance with the FIDE rules when a dead position is reached.)
fjdkslagh wrote:
Both sides actually have more than enough captures to set up the pawns:
I might not check over my positions sometimes, but I can still make something that is illegal:
But just not this time.