We know that a pin is when a less valuable piece is attacked by a long rang piece while defending a higher valuable piece such that movement of the piece subjects the more valuable piece to attack.
We know that a skewer is the opposite, in terms of piece value attacked.
But what if the pieces are of same value? For example, a bishop attacking a rook on a diagonal with another rook on same diagonal with no pieces between the rooks (but not forked).
Is there a special term for this?
That is a very good question. :)
I don't think there is a term for that type of attack as far as I know. However, I think it can be considered a pin if the position is right, and the same goes for a skewer. Sometimes it is best for that first piece under attack to move out of the was to avoid a big loss, and sometimes it is best for that piece to stay put. There are also times where you have a choice on which way you want out of it. :)
Of course, something like this would go both ways:
Good question but I always thought of it as a skewer more than a pin
isnt that a fork? because youre attacking a stronger piece than the attacker piece, but if it moves, you will attack a stronger piece than your attacker piece, so that should be called a fork i think, in spanish i use to say "clavada" for the same motif.
Like a knight "forking" two pieces like a bishop "forking" two pieces
i dont think bishop can fork can it?
I think of them as linear attacks. pins and skewers are specific cases. in your example its just form of double attack I guess.
I would say it is both - the front Rook is pinned because the skewer picks up the back one. We could call it a pinewer or a skewin.
isn't this kind of a x-ray attack ?
The purpose of a pin is to limit mobility. The pinned piece can no longer be used as a defender, so you can attack the pieces it would otherwise be protecting, or you can get safe tranportation through squares that normally would be protected.The purpose of a skewer is to capture. I'd say 2 pieces of equal value are a skewer, not a pin. Whichever piece is moved you take the other one.