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

"40H-EPD-databases" is copyright (c) 2014-26. All rights reserved.

These databases are freeware. They contain chess positions from
the Public Domain 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 "epd" records, 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" checkmate puzzles consist of Chess positions presented in 
"epd" notation with the solution included in the opcodes. 

A PGN-Viewer is necessary since the puzzles are presented in "EPD"
format.

The object of a checkmate puzzle is to find the fastest (shortest)
path to checkmate.

Each puzzle has a forced checkmate in 2 to 8 moves. 

The "40H" checkmate puzzles are organized into 14 data files:

mate-b2.epd, mate-b3.epd, mate-b4.epd, mate-b5.epd, mate-b6.epd,
mate-b7.epd, mate-b8.epd

mate-w2.epd, mate-w3.epd, mate-w4.epd, mate-w5.epd. mate-w6.epd,
mate-w7.epd, mate-w8.epd
 
For example, "mate-w3.epd" contains positions where there is a 
forced shortest checkmate for "White" in "3" moves.

Each puzzle has a flipped version in the other color, with the 
same "id" number. The flipped puzzle versions are logically the
same.

There are 37,000+ chess puzzles in this collection, divided 
equally between "White to move" and "Black to move". 

The puzzles are NOT rated or arranged by difficulty. They are
arranged alphanumerically. 

Editing: 
1. Maximum material advantage for the checkmating side is 2 pawns 
or equivalent.
2. No multiple winning moves in the starting position. 
3. NO duplicate positions. 
4. NO duplicate predicted variations (pv opcode).
5. NO false "en passant" notations.
6. Missing "Castling" permissions restored if the King and Rook
are in Castling position.

When using a PGN Viewer:
1. Do NOT assume "en passant" permission exists. Check the "epd" 
record.  
2. "Castling" permissions always exist if the King/Rook are in 
Castling position.           . 
 
Opcodes:
Each puzzle "epd" record has a "bm", "pv", "ce" and "id" opcode.

Each puzzle has a unique best first best move. That best move 
("bm" opcode) leads to the shortest (fastest) checkmate. Solutions 
having more than one best first move have been excluded. 

The predicted variation ("pv" opcode) lists one shortest checkmate 
path starting with the "best (first) move". There can be others,
but they are not listed.

The centipawn evaluation ("ce" opcode) indicates the numerical 
advantage/disadvantage of the position in centipawn units from the
viewpoint of White. Due to the impending checkmate, "ce" has been 
converted to an alternative form that shows the minimum number of 
moves for a forced checkmate. Examples: "ce +M4;" means White 
has a 4-move "shortest" path to checkmate, "ce -M3;" means 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 in
the corresponding file of the other color. The flipped versions
with the same "id number" are logically equivalent puzzles.

Miscellaneous:
A "PGN Viewer" is a necessity.
"bm" and "pv" moves are in LAN (long algebraic notation).
  
Sources:
The positions in this collection were found in the Public Domain. 

Software:  
Software used consisted 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.
 
To Report Problems: rc1242@yahoo.com

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