a diagonal at any distance — and the half of the board that will never come
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
The moves are FIDE Laws of Chess in force from 1 January 2023, article 3. Square counts are walked, not quoted.
The bishop moves along diagonals, and a diagonal never changes the colour of a square. A bishop that began on a dark square therefore stays on dark squares to the end of the game: thirty-two of the sixty-four squares are beyond it for any number of moves. This follows from the move itself, not from any position.
It can be checked by walking rather than by reasoning: set out from a1 along every diagonal available, repeat until no new squares appear, and exactly thirty-two are collected — all of them the colour of a1. That walk is what stands in this sheet's checks.
Hence a pair of bishops is worth more than two bishops. One covers half the board; two of opposite colours cover all of it; two of the same colour remain half the board however many there are. Hence too the notion of a «bad» bishop: it runs into its own pawns standing on its colour, and it cannot change colour.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 7 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
four FIBA sizes with their circumference and mass — and why the rules set a bounce, not a pressure
Law 2, three codes of the game, five sizes and three FIFA quality marks — what a ball must survive
eleven sports at true relative size — circumference, mass, pressure, and who sets them
one square in any direction, from three in the corner to eight in the middle, and castling