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Victory Conditions

The game has two distinct win conditions depending on which side achieves their objective first.

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Mouse Wins

The mouse achieves victory when it reaches the cats’ starting row. Winning condition:
  • The mouse must reach row 8 (the opposite side of the board)
  • It can be on any black square in row 8
  • Specifically, any of these positions: (8,1), (8,3), (8,5), or (8,7)
These are the same squares where the cats started the game. The mouse essentially needs to “break through” the cats’ defensive line and reach their home row.
From the official rules:
“Gana el ratón si consigue llegar al lado contrario, es decir, a cualquiera de las casillas de las que salieron los gatos.” (The mouse wins if it manages to reach the opposite side, that is, any of the squares from which the cats started.)

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Cats Win

The cats achieve victory when they trap the mouse. Winning condition:
  • The mouse has no legal moves available
  • All four diagonal squares adjacent to the mouse are either:
    • Occupied by cats
    • Outside the board boundaries
    • White squares (not playable)
Unlike some games, there is no “capture” mechanic. The cats don’t remove the mouse from the board—they simply need to eliminate all possible moves.
From the official rules:
“Ganan los gatos si consiguen atrapar al ratón, de manera que el ratón no pueda moverse más.” (The cats win if they manage to trap the mouse, such that the mouse can no longer move.)

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How the Game Ends

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Mouse Victory Scenario

If the mouse successfully reaches row 8:
  1. The final board position is displayed
  2. The game announces the mouse’s victory
  3. The game session ends
Example winning position: 
 ------- ------- ------- ------- ------- ------- ------- -------
|       |(_)_(_)|       | . . . |       | . . . |       | . . . |
|       | (o o) |       | . . . |       | . . . |       | . . . | 8
|       |==\\o/==|       | . . . |       | . . . |       | . . . |
 ------- ------- ------- ------- ------- ------- ------- -------
The mouse has reached row 8 and wins!

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Cat Victory Scenario

When the cats successfully trap the mouse:
  1. The final board position is displayed
  2. A “Game Over” message is shown
  3. The game session ends
Example losing position: 
 ------- ------- ------- ------- ------- ------- ------- -------
| /\\_/\ |       | /\\_/\ |       | . . . |       | . . . |       |
|( o.o )|       |( o.o )|       | . . . |       | . . . |       | 5
| > ^ < |       | > ^ < |       | . . . |       | . . . |       |
 ------- ------- ------- ------- ------- ------- ------- -------
|       |(_)_(_)|       | /\\_/\ |       | . . . |       | . . . |
|       | (o o) |       | . . . |       | . . . |       | . . . | 4
|       |==\\o/==|       | . . . |       | . . . |       | . . . |
 ------- ------- ------- ------- ------- ------- ------- -------
| . . . |       | /\\_/\ |       | . . . |       | . . . |       |
| . . . |       | . . . |       | . . . |       | . . . |       | 3
| . . . |       | . . . |       | . . . |       | . . . |       |
 ------- ------- ------- ------- ------- ------- ------- -------
The mouse at (4,2) is surrounded by cats and has no valid moves—the cats win!

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Understanding Trapped Positions

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What Constitutes Being Trapped

A mouse is trapped when all four diagonal directions are blocked: For a mouse at position (row, col), it checks:
  • Forward-left: (row+1, col-1)
  • Forward-right: (row+1, col+1)
  • Backward-left: (row-1, col-1)
  • Backward-right: (row-1, col+1)
If all four positions are either occupied by cats or invalid (outside board), the mouse is trapped.

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Example Trap Formations

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Corner Trap

When the mouse is in a corner, it only needs 2 cats to be trapped: 
Position (1,2):
- Cannot go to (0, 1) - outside board
- Cannot go to (0, 3) - outside board
- Cat at (2, 1)
- Cat at (2, 3)
= Trapped!

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Edge Trap

When the mouse is on an edge but not a corner, it needs 3 blocking positions: 
Position (1,4):
- Cannot go to (0, 3) - outside board
- Cannot go to (0, 5) - outside board
- Cat at (2, 3)
- Cat at (2, 5)
= Trapped!

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Center Trap

When the mouse is in the center of the board, all 4 diagonal squares must be blocked: 
Position (4,4):
- Cat at (3, 3)
- Cat at (3, 5)
- Cat at (5, 3)
- Cat at (5, 5)
= Trapped!
The AI in this implementation uses sophisticated strategies to force the mouse into trapped positions, achieving a 100% win rate against human players.

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Win Detection

The game automatically detects win conditions after each move:

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After Mouse Moves

The system checks:
  1. Has the mouse reached row 8?
  2. If yes → Mouse wins
  3. If no → Cat’s turn begins

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After Cat Moves

The system checks:
  1. Does the mouse have any legal moves?
  2. If no legal moves → Cats win
  3. If legal moves exist → Mouse’s turn begins

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AI Strategy Insights

The CLIPS expert system uses multiple rule-based strategies to trap the mouse:
Cats advance together in a coordinated line, maintaining formation to limit the mouse’s forward progress. The AI identifies which cat should move to maintain an unbroken diagonal barrier.
When the mouse is positioned between cats, the AI recognizes the opportunity to tighten the trap by moving the appropriate cat closer.
If a cat is more than 2 columns away from the mouse, it advances diagonally toward the mouse to prevent easy escapes around the flanks.
The source code reveals that the AI evaluates multiple strategies with different priority levels (salience values), ensuring the most effective move is chosen each turn.

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Strategic Implications

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For the Mouse Player

To have any chance of winning:
  • Avoid being cornered early in the game
  • Create multiple escape routes at all times
  • Force cats to spread out rather than maintaining formation
  • Use backward moves strategically since cats cannot follow
  • Push through gaps in the cat formation before they close

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Game Difficulty

According to the source documentation:
“El sistema presenta la inteligencia artificial de las piezas de los gatos, de manera que un 100% de las partidas son ganadas por los gatos.” (The system features artificial intelligence for the cat pieces, such that 100% of games are won by the cats.)
This makes the game extremely challenging—the AI plays perfectly, so finding a winning path requires exceptional play from the human player.
While the AI is designed to achieve a 100% win rate, creative and strategic play might still find edge cases or force draws. The game serves as an excellent example of expert system design and game AI.

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