Mat Plus Glossary
Mat Plus

Glossary

(Note: this text is under construction and so far contains only some basic explanations)
Chess Problem
A position on the chess board with associated stipulation, i.e. Mate in 2 moves, Helpmate in 3 moves etc. Normally, there should be only one way to satisfy the stipulation, otherwise problem is unsound (cooked). Sometimes, typicaly in helpmates, there are two or more solutions stipulated. Mat Plus accepts direct mate, helpmate and selfmate original problems.
Direct mate problems
In direct mate problems white plays first and for every black defence mates not later than in given number of moves. The stipulation is "Mate in n moves", or shorter "Mate in n", or symbolically "#n".
Helpmate problems
In helpmate black begins and helps white to mate him (black) in given number of moves. The stipulation is "Helpmate in n moves", or shorter "Helpmate in n", or symbolically "h#n".
Selfmate problems
In selfmate problems white plays first and for every black defence forces black to mate him (white) not later than in given number of moves. The stipulation is "Selfmate in n moves", or shorter "Selfmate in n", or symbolically "s#n".

Terms and Symbols

Key move
The move that solves the problem (or triggers the solution of the problem).
Threat
The line which would solve the problem after illusive black random (or non-defending) move.
Block
Problems without threat but each black move carries the weakness which white can utilize.
Solution
Key move, threat and all variations starting with black moves which are defences against the threat. In block problems each black move starts a variation.
v (Try)
In direct mates and selfmates: a move which almost solves the problem, but just fails to unique black defence. In helpmates: a sequence of moves which fails due to the lack of tempo move(s) in the course of play.
* (Set play)
Play before the first move of the solution, i.e. in direct twomover mates set for black moves before the key. In helpmate: the line which would solve the problem if white is to play, but cannot be realized due to the lack of black tempo-move.
n111... (n solutions)
In helpmate: there are n different lines starting with first move of black that solve the problem.
1n11... (n variations)
In helpmate: there are n different lines starting with first move of white that solve the problem.
11n1... (n variations)
In helpmate: there are n different lines starting with second move of black that solve the problem.
0111... (n variations)
In helpmate: alternate symbol for Set play, or for stipulation "White begins".
W-->
"White begins". Overrides default helpmate convention that black plays first.
B-->
"Black begins". Overrides default direct mate or selfmate convention that white plays first.
b), c)... (twins)
Twins are two or more positions of the same problem which differ in a small detail, i.e. changed position of one piece, added or removed piece, exchanged places of two pieces, piece replaced by another end similar. For instance:
b) WKb1-->c2: position (b) arises from diagram position when white King is moved from b1 to c2;
c) -WPd4: position (c) arises from diagram position when white Pawn is removed from d4;
+c) WRa4=WS: position (c) arises from position (b) when white Rook a4 is replaced by white Knight;
+c) WSa4: slightly extended meaning - whatever was on a4 is now replaced by WS;
b) +BPd6: position (b) arises from diagram position when black Pawn is added on d6;
b) WBd4<-->BBf6: position (b) arises from diagram position when two bishops exchange their places;
etc., etc.
duplex
Stipulation for both sides, i.e., "h#2 duplex" means it is also requested to find how white can begin and help black to mate him (white) in two moves.