Compositional play is often multi-phase. The diagram may already contain set play; a near-key may create try play and fail to one refutation; the actual key creates the post-key solution.
A solver therefore reads not one line but a formal comparison:
set → try/virtual → actual
The key is defined by its role in the stipulated solution, not by how spectacular or quiet it looks.
Key
The key is the first move of the author's solution in a problem. Its compositional value depends on what play it creates or transforms; a key is not defined as the strongest chess move in the practical sense.
Threat
A threat is the continuation White intends if Black makes no relevant defense after the key. A threat problem structures Black's play around defenses that defeat or alter that threat.
Defense
A defense is a Black reply that answers the threat or otherwise materially changes the solution structure and therefore requires a specific continuation.
Variation
A variation is a distinct solution branch generated by a relevant defense and White's required continuation. Formal thematic relationships often compare variations.
Actual / Post-Key Play
Actual/post-key play is the solution after the real key. It is compared with set/try phases to identify changed, transferred, reciprocal or cyclic relationships.
Threat Problem
A threat problem has a key that creates a threat; Black defenses defeat that threat but permit corresponding mating/solution continuations.
Block Problem
In a block, the diagram/key leaves Black with moves that each create a specific weakness; the solution often works because Black is compelled to disturb a prepared defensive balance.
Zugzwang Structure
In compositional zugzwang, the side to move is harmed by the obligation to move. It is a formal play structure, not merely a difficult practical position with no pleasant move.
Set Play
Set play is play already prepared in the diagram before the key, commonly examined by hypothetically giving the defending side the move. It is content of the composition even though it is not the actual post-key solution.
Try
A try is a near-solution that would satisfy the thematic plan except for a specific Black refutation. A genuine try is not just any failed candidate.
Refutation
The refutation is the defense that defeats a try. The relationship between try threats/mates and later actual play can itself form a theme.
Virtual Play
Virtual play includes non-actual thematic phases such as tries and related hypothetical play used to express formal relationships.
Twin
A twin creates a related composition by a stated change to the diagram—moving/adding/removing/changing a unit or another explicit transformation—usually with its own intended solution.
Multiple-Solution Phase
Map Multiple-Solution Phase into a phase table rather than a move list. Record which defense/continuation/function appears in set, try and actual play, then state what formal relationship changes or persists.
Phase Comparison
Compare which defenses, threats, mates or functions appear in set, try and actual play. The artistic content often lies in what changes while the underlying matrix remains related.
Changed Play
Changed play occurs when the same defense is answered differently in another phase. The exact named theme depends on the formal mapping, not merely on different moves happened.
Transferred Play
Transferred play moves a thematic continuation or function from one defense/context to another across phases.
Reciprocal Play
Reciprocal play exchanges roles between two elements—commonly defenses, threats, mates or functions—across phases.
Cyclic Play
Cyclic play rotates three or more thematic elements in an ordered mapping across variations or phases rather than merely swapping two.
Changed Functions
Map Changed Functions into a phase table rather than a move list. Record which defense/continuation/function appears in set, try and actual play, then state what formal relationship changes or persists.
Phase-Reading Tables
Map Phase-Reading Tables into a phase table rather than a move list. Record which defense/continuation/function appears in set, try and actual play, then state what formal relationship changes or persists.
Phase Practice
Map Phase Practice into a phase table rather than a move list. Record which defense/continuation/function appears in set, try and actual play, then state what formal relationship changes or persists.
Think in Phases, Not Just Lines
Many two-move and three-move problems are designed around relationships between phases. If you only write the post-key variations, you may solve the task while missing its artistic content. Build a small phase table: what happens in the diagram position, after each serious try, and after the key? Then compare the same black defenses across those phases.
This makes changed, transferred, reciprocal and cyclic play visible. The theme often lives not in any single mate but in the mapping defense → continuation as that mapping changes.
Key, Threat and Defense Are Functional Labels
A quiet first move is not automatically a “good key,” and a checking move is not automatically a bad one. Key quality depends on what the move changes: flights, pins, lines, self-block possibilities, battery effects and the thematic relationship to the rest of the solution. Likewise, a threat is not just “what White wants”; it is the continuation that would fulfil the stipulation if Black did nothing relevant.
A Try Must Almost Work
A random wrong move is not a try. A genuine try creates convincing thematic play and fails to a specific refutation. That refutation is part of the composition's content because it explains why the key is necessary. When studying tries, record both the attractive virtual play and the unique or thematic reason the attempt fails.
Phase Comparison as a Formal Map
When a problem contains set play, tries and actual play, make a table with black defenses as rows and phases as columns. Write the corresponding White continuation in each cell. This turns abstract labels into a visible mapping and makes several important structures easier to distinguish:
- changed play — the same defense receives a different continuation in another phase;
- transferred play — a continuation associated with one defense reappears against another;
- reciprocal play — two continuations exchange their defense relationships;
- cyclic play — three or more relationships rotate through a cycle.
The same diagram can contain more than one relationship, so avoid naming a theme before the entire phase map is visible.
Threat Problems, Blocks and Zugzwang Are Different Search Environments
After the key, a threat problem gives Black a reason to defend against a specific continuation. In a block, the important fact is that every available black move creates a weakness or permits a mate. A zugzwang structure can make the absence of a useful waiting move central to the construction. Solving becomes easier when you identify which environment you are in instead of assuming every problem has a conventional threat.
Flights Are Thematic Data
A key that gives the black king a flight can be more paradoxical than one that simply restricts it. Track which flights exist in set play, which are created or removed by the key, and which mates answer them. In many problems, the artistic point is not “the king gets a square” but the changed relationship produced by that new legal option.