Candidate Moves - chess term
Candidate Moves
Definition
“Candidate moves” are the short list of promising moves a player deliberately selects for deeper calculation during their thinking process. Instead of trying to visualize every legal move in a position, strong players narrow their focus to 2–5 candidate moves that appear most likely to achieve their strategic or tactical goals. The concept was popularized by the Soviet trainer Alexander Kotov in his classic manual Think Like a Grandmaster (1971).
How It Is Used in Chess
- Time-management tool: By reducing the branching factor, players conserve time on the clock and mental energy.
- Calculation framework: Once the list is fixed, each candidate line is examined to the end of the variation, ideally without jumping back and forth between moves.
- Error-checking device: After calculating a candidate line, players compare the resulting evaluations (better, equal, worse) and pick the best.
- Training discipline: Many coaches insist that students verbalize or write down their candidate moves before calculating—an exercise that mirrors tournament conditions.
Strategic Significance
The candidate-move method is central to grandmaster decision-making and underlies most modern engines’ search algorithms (e.g., alpha–beta pruning begins with a “move ordering” phase similar to human candidate selection). Mastery of this concept often marks the transition from club strength to expert level because it:
- Prevents analysis paralysis.
- Sharpens tactical vision by forcing concrete calculation.
- Integrates strategic plans with concrete moves.
Origins & Historical Development
While strong players have always intuitively limited their search, the explicit term “candidate move” enters chess literature through Kotov. His two-step method— (1) find all candidate moves, (2) analyze them one by one without returning to the list—became a staple of Soviet training curricula and influenced generations of grandmasters, including Garry Kasparov. Today the idea is taught worldwide, sometimes refined into “expanded candidates first, narrow candidates later” to reduce missed opportunities.
How to Generate Candidate Moves
- Checks, Captures, Threats (CCT): Start by listing forcing moves.
- Quiet improving moves: Look for plans that improve worst-placed pieces or create strongholds (e.g., 1. Rd1 to occupy an open file).
- Strategic triggers: Identify structural or king-safety targets (weak pawns, exposed king, outposts) and propose moves that exploit them.
- Elimination & comparison: Discard moves that obviously fail strategically or tactically; rank the rest by plausibility.
Illustrative Example
Position (White to move):
Pieces: White Kg1 Qd1 Rb1 Re1 Bf3 Nd5 Pa2 Pb2 Pc2 Pg2 Ph2
|
Black Kg8 Qd6 Ra8 Re8 Bf7 Nc6 Pa7 Pb7 Pc7 Pf6 Pg7 Ph7
FEN: r4r1k/ppp2bp1/2qn1p2/3N4/8/5B2/PP3PP1/1RBQR1K1 w - - 0 1
Candidate-move search might yield:
- 1. Ne7+ Nxe7 2. Qxd6 cxd6 – wins a pawn but trades queens.
- 1. Nxf6+ Qxf6 2. Bxc6 bxc6 3. Qd7 – enters an endgame with an extra pawn.
- 1. Rxe8+ Rxe8 2. Ne3 – simple line leading to a small but stable edge.
After calculating, White might conclude that 1. Nxf6+! is the most promising because Black’s king becomes vulnerable.
Famous Game Reference
In Kasparov vs. Topalov, Wijk aan Zee 1999, Kasparov’s immortal 24-move combination began with the candidate-move search in a double-edged middlegame. Kotov’s discipline enabled Kasparov to spot 24. Rxd4!!—a move commentators initially missed.
Common Pitfalls
- Forgetting a candidate line mid-calculation. Remedy: write or mentally “bookmark” the move list.
- Fixating on the first appealing move (a.k.a. “short-circuiting”). Remedy: force yourself to name at least two alternatives.
- Over-expanding the list (analysis paralysis). Remedy: prioritise moves by forcing nature and strategic needs.
Interesting Facts & Anecdotes
- Kotov once admitted blundering because he followed his own rule too rigidly; after analyzing three candidate moves “to the end,” he played a fourth move he had barely checked—only to lose instantly.
- Grandmaster Viktor Korchnoi claimed he could remember the exact number of candidate moves he considered during each move of his famous win against Petrosian in their 1974 Candidates match.
- Modern engines like Stockfish still rely on effective “candidate move ordering”—demonstrating that Kotov’s human insight remains at the heart of silicon calculation.
Quick Reference Checklist
- List forcing moves (CCT).
- Add strategic plans.
- Trim to 2–5 serious candidates.
- Analyze each line to a stable evaluation.
- Compare results and choose.