Editing Glossary of chess problems (section)

== D ==
{{glossary}}

{{term|term= directmate |content = directmate {{anchor|Directmate|directmates}} }}
{{defn|defn= A type of problem where White, moving first, is required to checkmate Black in a specified number of moves against any defence. Such a problem is usually indicated by the stipulation "mate in two" (or however many moves is necessary) or "checkmate in two". The term ''directmate'' distinguishes these sorts of problems from [[#helpmate|helpmates]], [[#selfmate|selfmates]], [[#reflexmate|reflexmates]] and others.}}

{{term|term= domination |content = [[Domination (chess)|domination]] {{anchor|Domination}} }}
{{defn|defn= In [[study (chess)|studies]], a situation whereby a piece has relatively wide freedom of movement but nevertheless must be lost.}}

{{term|term= doubling |content = doubling {{anchor|Doubling}} }}
{{defn|defn= A manoeuvre in which two pieces are placed on the same line (rank, file or diagonal) such that they support each other. Special cases are [[#Turton doubling|Turton doubling]] and [[#Zepler doubling|Zepler doubling]].}}

{{term|term= dual |content = dual {{anchor|Dual|duals}} }}
{{defn|defn= Ideally, White should have only one move at each juncture that solves a problem (unless the plan is conceptual such as in the well-known "[https://www.youtube.com/watch?v=C1pn5lj13HA&list=PL3NxPgqsWUxdeBRVUuyBvbf1BOaCJ3e2X&index&#124; Trojan Horse Puzzle]" study by Ben Schultz).<ref>{{cite web | url=https://www.youtube.com/watch?v=C1pn5lj13HA&list=PL3NxPgqsWUxdeBRVUuyBvbf1BOaCJ3e2X&index | title=A Viewer Tricked Me with This Puzzle | website=[[YouTube]] | date=November 2022 }}</ref> Barring examples such as these, if White has an alternative at any stage but the first move, this is a ''dual''; if multiple winning moves are available at the start, this is a [[#cook|cook]].<ref>{{Cite book |last=Cheng |first=Ray |title=Practical Chess Exercises |year=2019 |pages=11 |language=en}}</ref><ref>{{Cite book |last1=Hooper|first1=David Vincent|last2=Whyld|first2=Lenneth |title=The Oxford Companion to Chess |publisher=Oxford University Press |year=1996 |pages=109 |language=en}}</ref> A dual is not as serious of a flaw as a cook; and, in minor lines, duals may be permissible (although opinions differ on this point). Some problems make a virtue out of ''dual avoidance'': of two apparently equivalent White moves, only one works.}}

{{term|term= duplex |content = duplex {{anchor|Duplex|duplexes}} }}
{{defn|defn= A type of problem in which there are two solutions, the second one reversing the roles of the colours in the first. The most common type is the duplex [[#helpmate|helpmate]], in which the two solutions are: Black moves first and cooperates with White to be mated; and White moves first and cooperates with Black to be mated.}}

{{glossary end}}