Three chess rules which i can't understand . so need help.

[Terry McCracken]

4. Since a King is allowed to castle with each of the rooks on its flanks, why shouldn't the King be allowed to castle with a King pawn promoted to a rook? (assuming it meets the usual requirements of not being in check, not passing through check, etc)

Talk about a Looooong Castle In the Middle of the board no less

[hgm]

4. Since a King is allowed to castle with each of the rooks on its flanks, why shouldn't the King be allowed to castle with a King pawn promoted to a rook? (assuming it meets the usual requirements of not being in check, not passing through check, etc)

I once knew a chess program that would castle with an opponent's rook, if the opponent had just undr-promoted to one in a corner square. After all, that rook hadn't moved yet...

It might be of interest that the oldest known precursor of Chess, the Indian game of Chaturanga, already had a rule somewhat similar to castling: Once in the game the King was allowed a Knight's jump, provided it had not been checked yet. (Even if it had moved!) No doubt the move served the same function as modern castling.

So not allowing such moves in cases of check actually has very deep roots.

Concerning e.p. capture: actually the rulse that forbids castling when the King passes an attacked square is a form of e.p. capture of the King! Apparently a piece that is granted an unusual double move is allowed to be captured on the square it skipped, by a lower or equal piece. For a King of course all pieces are lower or equal, and since it is not allowed to expose your King to capture, that makes castling in such a case illegal.

In some blitz tournaments, btw, putting your king in check is simply considered a blunder on which you can claim the game. As you can on every other illegal move.

[Mike S.]

2. Why pieces other than pawns can't capture the 2 squares moved pawn by moving into the first square . ?
(en passant).

The sense of the doublestep, or 2-squares-move of the pawns is to speed up the opening. But we don't want that a passed pawn can be created by that:

[d]8/8/8/8/p7/8/1P1k4/1K6 w - - 0 1

Without e.p. rule, White could win with 1.b4 passing Black's a4 pawn, but that is not the purpose of the 2 squares-rule for the first pawn move. So, 1...axb3 would capture en passant here, 2.Kb2 draw.

[George Tsavdaris]

2. Why pieces other than pawns can't capture the 2 squares moved pawn by moving into the first square . ?
(en passant).

The sense of the doublestep, or 2-squares-move of the pawns is to speed up the opening. But we don't want that a passed pawn can be created by that:

[d]8/8/8/8/p7/8/1P1k4/1K6 w - - 0 1

Without e.p. rule, White could win with 1.b4 passing Black's a4 pawn, but that is not the purpose of the 2 squares-rule for the first pawn move. So, 1...axb3 would capture en passant here, 2.Kb2 draw.

If the ONLY purpose for en-passant move is not to let a passed Pawn to be created, then why in the following position after c4 black Bishop can't capture en-passant?

If the en-passant move has been created not to let a side to create a passed Pawn then black Bishop should be allowed to capture en-passant Bxc3ep. But black Bishop is not allowed to do that, so the reason for en-passant should be different one.

[d]8/B7/8/8/1b1p4/8/2P5/2K3k1 w - - 0 1

[hgm]

Mike's theory sounds kind of logical, though. Why would you need to capture with the Bishop if you can also do the capture with the Pawn? If there is no Pawn to do the e.p. capture, the double move did not create a passer (if it wasn't already a passer after a single move).

Allowing only Pawns to capture e.p. is the minimal rule change that you need to give the double move minimal consequences in endings.

[George Tsavdaris]

Mike's theory sounds kind of logical, though. Why would you need to capture with the Bishop if you can also do the capture with the Pawn?

You didn't observe the position well enough.
The black Pawn can't capture en-passant since it is pinned by the white Bishop. Look where black King is....

So if the black Bishop does not capture it en-passant a passed Pawn will be created....But this is not allowed.
If the passed Pawn idea was the only reason then Bishop should be allowed to capture en-passant.

[Mike S.]

So if the black Bishop does not capture it en-passant a passed Pawn will be created....But this is not allowed.
If the passed Pawn idea was the only reason then Bishop should be allowed to capture en-passant.

Having a rule with an idea behind it, doesn't require that it achieves it's goal in any, even the most exceptional case. - In your witty example, we can say it is so because the rule that it's not allowed to put the own king in check, ranks higher.

From The Oxford companion to chess (Hooper / Whyld 1992):

pawn, (...) So that a pawn making it's first move cannot evade capture, by a pawn on an adjoining file the EN PASSANT law was introduced.

Their wording is more correct than mine because they don't mention passed pawns directly but only captures by an adjoining pawn. But of course, it's against getting a passer "for free" (kind of)...

[Terry McCracken]

2. Why pieces other than pawns can't capture the 2 squares moved pawn by moving into the first square . ?
(en passant).

The sense of the doublestep, or 2-squares-move of the pawns is to speed up the opening. But we don't want that a passed pawn can be created by that:

[d]8/8/8/8/p7/8/1P1k4/1K6 w - - 0 1

Without e.p. rule, White could win with 1.b4 passing Black's a4 pawn, but that is not the purpose of the 2 squares-rule for the first pawn move. So, 1...axb3 would capture en passant here, 2.Kb2 draw.

The rule was made for all aspects of the game, especially the ending, like the position you cite.

It cuts both ways and makes chess King + Pawn endings more interesting, more complex. You must take into account this possibility well in advance. Change it and you change chess. I think chess has evolved very well and other variants although interesting isn't necessary as chess is still too complex to play anyway near to perfection. Maybe in time, but not today.

Terry

[ChessMate]

Do you think its more natural and much more simple that we don't allow the pawns a double step when there is a opposition pawn adjacent 2 squares up.
As we can't able to castle when king is passing through check so when pawn has to pass through a pawn's attack line don't allow it double move.

[Vempele]

Do you think its more natural and much more simple that we don't allow the pawns a double step when there is a opposition pawn adjacent 2 squares up.
As we can't able to castle when king is passing through check so when pawn has to pass through a pawn's attack line don't allow it double move.

By that logic, we should also forbid moves that allow the moving piece to be captured, as kings can't do that either.

I suppose one reason a king can't castle through an attacked square is that it could be 'captured en passant' if it did.