readme for "40H-EPD-databases", edited by Norman Pollock

"40H-EPD-databases" is copyright (c) 2014-25. All rights reserved.

These databases are freeware. They contain chess positions 
available in the Public Domain on the Internet or elsewhere, and 
were edited by Norman Pollock.

No warranty, expressed or implied, is made that the information 
provided in "readme-epd-db.txt" or in the positions, is accurate. 

No warranty, expressed or implied, is made as to the worthiness 
of these files for computer or chess usage. 

The user bears full responsibility for any consequences from 
the use or misuse of these files. The editor is not responsible 
for any damages or losses of any kind.

These databases can be freely distributed provided they are 
distributed "as is". The editor is not responsible for any 
changes made by others.

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Overview:

"40H-EPD-databases" contains "realistic" Classical Chess checkmate 
puzzles from 2 to 7 moves. The vast majority of these positions
occurred in actual games between high-level players.

The object of each checkmate puzzle is to find a checkmate path
in the shortest number of moves. 

A "PGN Viewer" is needed to "see" the positions that are in the
files.

The checkmate puzzles are organized into 12 basic files:

mate-b2.epd, mate-b3.epd, mate-b4.epd, mate-b5.epd. mate-b6.epd, 
mate-b7.epd
  
mate-w2.epd, mate-w3.epd, mate-w4.epd, mate-w5.epd. mate-w6.epd, 
mate-w7.epd
 
For example, "mate-b3.epd" contains positions where there is a 
forced mate for "Black" in "3" moves, where "3" is the shortest 
possible number of moves.

There are 5 extra files: mate-all.epd (all positions), mate-all-w.epd
(all positions with White to move), mate-all-b (all positions with
Black to move), mate-all-sort.epd (all positions sorted), and 
mate-all.pgn (pgn games using FEN tags).

A material advantage for the attacking side, if it exists, is 
limited to a maximum of +2 pawns or equivalent, e.g. rook vs knight. 

Faux (or false) "en passant" squares have been removed.

There are no duplicate positions.

Each "epd" record (puzzle) has a unique "bm" opcode ("best move"),
a "ce" opcode ("centipawn evaluation" which has been converted
to "moves to mate"), a "pv" opcode ("predicted variation") 
and an "id" opcode. 

"bm" and "pv" output is in LAN (long algebraic notation) instead
of the more common SAN (short algebraic notation) for the purpose
of clarity.

Each of the puzzles in this collection has a unique best move. 
That best move ("bm") leads to the shortest (fastest) checkmate. 
Puzzles with more than one best move have been excluded. 

The predicted variation ("pv" opcode) lists a shortest checkmate 
path starting with the "best (first) move". There can be more than 
one "shortest" path, but each "shortest" path starts with the same 
"best move" and has the same number of moves. 

The centipawn evaluation ("ce" opcode) is evaluated from the 
viewpoint of White. This opcode indicates the numerical 
advantage/disadvantage of the position in centipawn units. 
Because of the impending checkmate, it has been converted to the 
minimum number of moves for a forced checkmate. For example, 
"ce +M4;" means White has a 4 move "shortest" path to checkmate. 
A negative value, such as "ce -M3;" indicates Black has a 3 move 
"shortest" path to checkmate.

The "id" opcode shows the "id" number created by the editor. 
Each record has a flipped version with the same "id" number. 
The two versions are logically equivalent. The flipped versions 
of the positions in "mate-wX.epd" are in "mate-bX.epd", and 
likewise.

Users should already be familiar with classical checkmating 
patterns. Many can be found at:

  https://en.wikipedia.org/wiki/Checkmate_pattern
  
The positions used in this collection were found in the Public 
Domain, and then edited. 
  
Thw software for this project consists of "ChestUCI v5.2" by 
Franz Huber (based on "CHEST v3.19" by Heiner Marxen), 
"Arena 3.5.1" by Martin Blume, "PGN-Extract" by David Barnes,
and "40H-EPD" tools by Norman Pollock.

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"40H-EPD-databases" has 2 download sites:

  40hchess.epizy.com

  nk-qy.info/40h  (Thanks to Frank Quisinsky)

Please bookmark.
 
contact: rc1242(at)yahoo(dot)com

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