Duo Trio Quart (Bitboards)
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Pawn-Duo, (Phalanx) [2]
two adjacent pawns of the same color on the same rank that mutually cover the other's stop square. A Trio are three horizontal friendly pawns, a Quart four horizontal friendly pawns.
Working in the bitboard centric world to determine pawn related pattern set-wise.
The code snippets rely on shifting bitboards, specially by one step only.
Neighbors
To get pawns with east or west neighbors is simple:
U64 pawnsWithEastNeighbors(U64 pawns) { return pawns & westOne (pawns); } U64 pawnsWithWestNeighbors(U64 pawns) { return pawnsWithEastNeighbors(pawns) << 1; // * 2 }
or
U64 pawnsWithWestNeighbors(U64 pawns) { return pawns & eastOne (pawns); } U64 pawnsWithEastNeighbors(U64 pawns) { return pawnsWithWestNeighbors(pawns) >> 1; }
♙♙♙ ♙♙ |
pawns pawns with east pawns with west pawns with east neighbors neighbors and west neighbors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1 . . . . . 1 1 . . . . . . . 1 1 . . . . . . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . 1 . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Neighbor Algebra
Pawns with east or west neighbors are at least member of a duo. Pawns with east and west neighbors at least member of a trio. If two neighbors have both east and west neighbors, it is at least a quart.
An exclusive pawn duo is therefor a pawn with one neighbor, while this neighbor has no other neighbor as well.
U64 duo (U64 pawns) { U64 withWestNeighbors = pawnsWithWestNeighbors(pawns); U64 withEastNeighbors = withWestNeighbors >> 1; U64 withOneExclusiveNeighbor = withWestNeighbors ^ withEastNeighbors; U64 withExclusiveWestNeighbor = withWestNeighbors & withOneExclusiveNeighbor; U64 withExclusiveEastNeighbor = withEastNeighbors & withOneExclusiveNeighbor; U64 duoWestOne = withEclusiveEastNeighbor & (withEclusiveWestNeighbor >> 1); U64 duoEastOne = duoWestOne << 1; return duoWestOne | duoEastOne; }
pawns pawns with excl. pawns with excl. duo east neighbor west neighbor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 1 . . . . . 1 . . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 . . . . . . 1 . . . . . . . . 1 . . . . . . 1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
See also
Forum Posts
- The phalanx concept by Lyudmil Tsvetkov, CCC, May 21, 2014
External Links
- Pawn Structure (General) | Page 5 of 5 | Phalanx Formation
- Duet from Wikipedia
- Phalanx from Wikipedia
- Trio from Wikipedia
- Kinga Głyk Trio - Walking Baby, VisionInMusica, Terni, March 10, 2017, YouTube Video
- Quart (disambiguation) from Wikipedia
- Panta Rhei plays Bartók's Quarts, 1977, YouTube Video