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Overview

Pawn structure analysis identifies recurring pawn formations in your games, providing insights into positional patterns and strategic themes. The system recognizes both generic structural motifs (isolated pawns, passed pawns) and named structures (Carlsbad, Maróczy Bind).

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Structure Identification

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Pawn Structure Signature

Each position is reduced to a pawn-only signature for pattern matching: 
// src-tauri/src/pawn_structures.rs:675
fn pawn_structure_signature_from_fen(fen: &str, mode: &str, player_color: Color) -> String {
    // Extract only pawn placement from FEN
    // Example: "8/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/8"
}

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Analysis Modes

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pawn_structure_mode
enum
default:"both"
Structure analysis mode:
  • player: Analyze only the player’s pawns
  • both: Analyze both sides’ pawn structures
// Keep only player's pawns, normalize to 'P'
"8/8/8/8/4P3/8/PPPP1PPP/8"

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Structural Motifs

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Detected Motifs

The system detects the following pawn structure characteristics:
Pawn Islands: Groups of pawns separated by empty files
fn count_pawn_islands(ps: &PawnSets) -> u8 {
    let mut islands = 0u8;
    let mut in_island = false;
    for f in 0..8 {
        let has = ps.file_counts[f] > 0;
        if has && !in_island {
            islands += 1;
            in_island = true;
        } else if !has {
            in_island = false;
        }
    }
    islands
}
Triggered when: 3+ pawn islands detected
Isolated Pawn: A pawn with no friendly pawns on adjacent files
fn has_isolated_pawn(ps: &PawnSets) -> bool {
    for f in 0..8 {
        if ps.file_counts[f] == 0 { continue; }
        
        let left = if f > 0 { ps.file_counts[f - 1] } else { 0 };
        let right = if f < 7 { ps.file_counts[f + 1] } else { 0 };
        
        if left == 0 && right == 0 {
            return true;
        }
    }
    false
}
Weakness: Cannot be defended by other pawns
Doubled Pawns: Multiple pawns on the same file
fn has_doubled_pawns(ps: &PawnSets) -> bool {
    ps.file_counts.iter().any(|&c| c >= 2)
}
Weakness: Reduced mobility, harder to defend
Passed Pawn: A pawn with no enemy pawns blocking its advance
fn is_passed_pawn(color: Color, ps: &PawnSets, opp: &PawnSets, file: usize, rank: usize) -> bool {
    let files = [file.saturating_sub(1), file, (file + 1).min(7)];
    match color {
        Color::White => {
            // Check if opponent has pawns ahead on adjacent files
            for f in files {
                for r in (rank + 1)..8 {
                    if opp.squares[f][r] { return false; }
                }
            }
            true
        },
        // ...
    }
}
Strength: Major endgame advantage
Connected Passed Pawns: Two passed pawns on adjacent files
fn has_connected_passed_pawns(color: Color, ps: &PawnSets, opp: &PawnSets) -> bool {
    // Identify all passed pawns by file
    let mut passed_by_file: [bool; 8] = [false; 8];
    for f in 0..8 {
        for r in 0..8 {
            if ps.squares[f][r] && is_passed_pawn(color, ps, opp, f, r) {
                passed_by_file[f] = true;
            }
        }
    }
    
    // Check for adjacent passed pawns
    for f in 0..7 {
        if passed_by_file[f] && passed_by_file[f + 1] {
            return true;
        }
    }
    false
}
Strength: Very powerful, often decisive
Hanging Pawns: Pawns on c4/d4 (or c5/d5) without support from b/e pawns
fn has_hanging_pawns(ps: &PawnSets) -> bool {
    let c = ps.file_counts[2] > 0;  // c-file
    let d = ps.file_counts[3] > 0;  // d-file
    let b = ps.file_counts[1] > 0;  // b-file
    let e = ps.file_counts[4] > 0;  // e-file
    c && d && !b && !e
}
Dynamic: Can be strength or weakness depending on position
Backward Pawn: A pawn behind adjacent pawns with its advance square attacked
fn has_backward_pawn(color: Color, ps: &PawnSets, opp: &PawnSets) -> bool {
    for f in 0..8 {
        for r in 0..8 {
            if !ps.squares[f][r] { continue; }
            
            // Check if adjacent pawns are more advanced
            let left_advanced = /* ... */;
            let right_advanced = /* ... */;
            if !(left_advanced || right_advanced) { continue; }
            
            // Check if advance square is attacked by enemy pawn
            let advance_rank = /* ... */;
            let attacked = /* check enemy pawn attacks */;
            
            if attacked { return true; }
        }
    }
    false
}
Weakness: Cannot advance safely
Isolated Queen Pawn: Pawn on d-file with no pawns on c/e files
fn has_iqp(ps: &PawnSets) -> bool {
    let d = ps.file_counts[3] > 0;  // d-file
    let c = ps.file_counts[2] > 0;  // c-file
    let e = ps.file_counts[4] > 0;  // e-file
    d && !c && !e
}
Complex: Dynamic play, often leads to middlegame attacks
Fianchetto: Classic kingside fianchetto pawn structure
fn has_fianchetto(color: Color, ps: &PawnSets) -> bool {
    match color {
        Color::White => {
            let g3 = ps.squares[6][2];  // g3
            let f2 = ps.squares[5][1];  // f2  
            let h2 = ps.squares[7][1];  // h2
            g3 && f2 && h2
        },
        // ...
    }
}
Strength: Solid kingside, bishop on long diagonal
Minority Attack: a+b pawns vs opponent’s a+b+c pawns
fn has_minority_attack_pattern(color: Color, ps: &PawnSets, opp: &PawnSets) -> bool {
    let has_a = ps.file_counts[0] > 0;
    let has_b = ps.file_counts[1] > 0;
    let opp_has_a = opp.file_counts[0] > 0;
    let opp_has_b = opp.file_counts[1] > 0;
    let opp_has_c = opp.file_counts[2] > 0;
    
    has_a && has_b && opp_has_a && opp_has_b && opp_has_c
}
Strategy: Attack queenside pawn majority

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Named Structures

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Recognized Structures

The system recognizes famous pawn structures from opening theory:

Carlsbad Structure

Classic Queen’s Gambit structure:
  • White: a2, b2, d4, e3, f2, g2, h2
  • Black: a7, b7, c6, d5, f7, g7, h7
Characterized by IQP and minority attack themes

Maróczy Bind

Sicilian structure with c4+e4 pawnsRestricts Black’s …d5 break

Hedgehog

Black setup: a6, b6, d6, e6Flexible, spring-loaded structure

Stonewall

White: c3, d4, e3, f4 Black: c6, d5, e6, f5Closed center, kingside attack

Scheveningen

Sicilian structure: c5, d6, e6Solid, flexible setup

Najdorf

Sicilian structure: a6, c5, d6Sharp, tactical positions

Dragon

Sicilian structure: g6, c5, d6Opposite-side castling attacks

Benoni

Black: c5, d6 vs White: d5Imbalanced structure

Benko

Gambit structure: a6, b5, c5Queenside pressure compensation

French

Black: d5, e6 vs White: d4, e5Closed center, space advantage

Slav

Black structure: c6, d5Solid Queen’s Gambit defense

Semi-Slav Triangle

Black structure: c6, d5, e6Rich middlegame positions

King's Indian

Black structure: d6, e5, g6Kingside pawn storm

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Filtering Structures

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Motif Filters

Filter games by specific pawn structure characteristics: 
const options: PawnStructureOptions = {
  player_ids: [123],
  pawn_structure_mode: 'both',
  structure_filters: [
    'isolated',          // Positions with isolated pawns
    'passed',           // Positions with passed pawns  
    'doubled'           // Positions with doubled pawns
  ],
  move_number: 20,     // Analyze structure after move 20
  // ...
};
Available motif filters:
  • islands - Multiple pawn islands (3+)
  • isolated - Isolated pawns
  • doubled - Doubled pawns
  • passed - Passed pawns
  • connected_passed - Connected passed pawns
  • hanging - Hanging pawns
  • backward - Backward pawns
  • minority_attack - Minority attack pattern
  • iqp - Isolated Queen Pawn
  • fianchetto - Fianchetto structure

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Named Structure Filters

Filter games by specific named structures: 
const options: PawnStructureOptions = {
  player_ids: [123],
  pawn_structure_mode: 'both',
  structure_name_filters: [
    'carlsbad',
    'maroczy_bind',
    'hedgehog'
  ],
  // ...
};
Available named filters:
  • carlsbad, maroczy_bind, hedgehog, stonewall
  • scheveningen, najdorf, dragon
  • benoni, benko, french
  • slav, semi_slav_triangle, kings_indian

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Filter Semantics

Motif filters use AND logic: All selected motifs must be present.Named structure filters use OR logic: Any selected structure matches.
let motifs_ok = if wanted_motif_mask == 0 {
    true
} else {
    (motif_mask & wanted_motif_mask) == wanted_motif_mask  // AND
};

let named_ok = if wanted_named_structure_mask == 0 {
    true
} else {
    (named_mask & wanted_named_structure_mask) != 0  // OR
};

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Structure Statistics

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Frequency Analysis

Track how often each structure appears: 
interface PawnStructureStat {
  structure: string;        // Pawn-only FEN signature
  frequency: number;        // Number of games with this structure
  win_rate: number;         // Win rate (0.0 - 1.0)
  sample_fen: string | null;  // Example position FEN
  games: PawnStructureGame[];  // Up to 50 sample games
}

interface PawnStructureGame {
  game_id: number;
  white: string;
  black: string;
  white_elo: number | null;
  black_elo: number | null;
  result: string;  // "1-0", "0-1", "1/2-1/2"
  fen: string;     // Full position FEN
}

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Win Rate Calculation

fn determine_win(result: &str, player_color: Color) -> f64 {
    match (result, player_color) {
        ("1-0", Color::White) | ("0-1", Color::Black) => 1.0,
        ("1/2-1/2", _) => 0.5,
        ("0-1", Color::White) | ("1-0", Color::Black) => 0.0,
        _ => 0.0,
    }
}

let win_rate = if frequency > 0 {
    total_wins / frequency as f64
} else {
    0.0
};

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Practical Examples

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Example 1: Isolated Pawn Performance

Find all games where you had an isolated pawn: 
const results = await invoke('compute_pawn_structures', {
  file: dbPath,
  options: {
    player_ids: [myPlayerId],
    pawn_structure_mode: 'player',  // Only my pawns
    structure_filters: ['isolated'],
    player_color: 'any',
    move_number: 15,  // Middle of opening
    date_range: 'OneYear'
  }
});

console.log(`IQP games: ${results.reduce((sum, s) => sum + s.frequency, 0)}`);
console.log(`Win rate: ${(results[0]?.win_rate * 100).toFixed(1)}%`);

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Example 2: Carlsbad Structure Performance

Analyze performance in Carlsbad structures: 
const carlsbad = await invoke('compute_pawn_structures', {
  file: dbPath,
  options: {
    player_ids: [myPlayerId],
    pawn_structure_mode: 'both',
    structure_name_filters: ['carlsbad'],
    move_number: 20,
    color_filter: 'white'  // As White only
  }
});

for (const stat of carlsbad) {
  console.log(`Games: ${stat.frequency}, Win rate: ${(stat.win_rate * 100).toFixed(1)}%`);
  console.log(`Sample games:`, stat.games.slice(0, 5));
}

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Performance Considerations

Large Database Warning: Structure analysis on databases with 10,000+ games may take several seconds. Consider:
  • Filtering by date range first
  • Using specific player IDs
  • Analyzing smaller move number ranges

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Optimization Tips

  1. Early filtering: Apply platform/time control filters before structure analysis
  2. Move number selection: Later move numbers (30+) have more unique structures
  3. Result limiting: The function returns top 20 structures by frequency
  4. Sample game limiting: Only 50 sample games are stored per structure

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