@EudaemonicPhonix said in #34:
Fascinating post! If you don't mind a request for a basic explanation (and apologies for being a dimwit).
Don't apologize. I have had similar questions.. And I see that you are struggling a bit through the text molasse too. All of this is best explained on a board. But we are using words beating around the bush to describe mathematically things that if not on board, in some other 2D medium as a sheet of paper, could represent positions as points and moves as links between those points. or other 2D representations of various chess concepts. Cycles of positions, cycles of moves, tempi counting..
Did you see @ambrona post where the same blog paragraph was laid without the obligatory natural language sentence syntax, in bullet form. Spacing things somehow transcending the left-right-linefeed-left right..
https://lichess.org/forum/community-blog-discussions/ublog-3MOYWXZY?page=3#27
Coming back to vampires. They are legal positions that become illegal when you mirror them.
The mirror operation does three things:
- Reflect the board horizontally with respect to the center.
- Invert the color of all pieces.
- Invert the turn (and castling/en-passant rights).
I went too fast fast-reading myself on the blog corresponding paragraph in my first pass, assuming that the mirror was a pure board perimeter square symmetry operation, as you seem to be doing by rotation. and the turn would be discussable. But the turn is part of the definition (the color-side to move).
I think given that we might, many of us jump on that visual meaning assumption, making the bullets points has been helpful emphasis, and might reach other people heavy on the geometry assumptions or general experience (chess or not).
The mirror is an operation on more than the board. It is about the chess quirks about time and timing of movers on the board. The turn base game. But, then why not call white black and black white, was my first recent reaction rereading the standard initial position being a vampire paragraph... well because vampire is not just about flipping it is about all retrograde possibilities not getting back to initial standard.
But ambrona, is likely to help you better.
edit: board reflection with respect to its ambient plane center horizontal line. The board being 8x8, its perimeter square figure, its border, lies in the board ambient space R2, and so are the whole board symmetry centers, chess board being a graph embedded in that ambient domain. If it were 9x9, then it center file and center rank and even the center point (=small square) would also be symmetry centers and on the board itself (not meaning there is no need for an ambient domain as well, but that it would not need evocation as much).
@EudaemonicPhonix said in #34:
> Fascinating post! If you don't mind a request for a basic explanation (and apologies for being a dimwit).
Don't apologize. I have had similar questions.. And I see that you are struggling a bit through the text molasse too. All of this is best explained on a board. But we are using words beating around the bush to describe mathematically things that if not on board, in some other 2D medium as a sheet of paper, could represent positions as points and moves as links between those points. or other 2D representations of various chess concepts. Cycles of positions, cycles of moves, tempi counting..
Did you see @ambrona post where the same blog paragraph was laid without the obligatory natural language sentence syntax, in bullet form. Spacing things somehow transcending the left-right-linefeed-left right..
https://lichess.org/forum/community-blog-discussions/ublog-3MOYWXZY?page=3#27
> Coming back to vampires. They are *legal* positions that become illegal when you mirror them.
> The mirror operation does three things:
> - Reflect the board horizontally with respect to the center.
> - Invert the color of all pieces.
> - Invert the turn (and castling/en-passant rights).
I went too fast fast-reading myself on the blog corresponding paragraph in my first pass, assuming that the mirror was a pure board perimeter square symmetry operation, as you seem to be doing by rotation. and the turn would be discussable. But the turn is part of the definition (the color-side to move).
I think given that we might, many of us jump on that visual meaning assumption, making the bullets points has been helpful emphasis, and might reach other people heavy on the geometry assumptions or general experience (chess or not).
The mirror is an operation on more than the board. It is about the chess quirks about time and timing of movers on the board. The turn base game. But, then why not call white black and black white, was my first recent reaction rereading the standard initial position being a vampire paragraph... well because vampire is not just about flipping it is about all retrograde possibilities not getting back to initial standard.
But ambrona, is likely to help you better.
edit: board reflection with respect to its ambient plane center horizontal line. The board being 8x8, its perimeter square figure, its border, lies in the board ambient space R2, and so are the whole board symmetry centers, chess board being a graph embedded in that ambient domain. If it were 9x9, then it center file and center rank and even the center point (=small square) would also be symmetry centers and on the board itself (not meaning there is no need for an ambient domain as well, but that it would not need evocation as much).