Math Problem Statement

Two players play a game on a board with 1 row and 117 columns. They take turns making moves. On each turn, a player can delete either a single square or two consecutive squares. Player 1 makes the first move. The player that makes the last move wins. Determine if any player has a winning strategy, and if so, who it would be.

Solution

To determine which player has a winning strategy, we can analyze the game using game theory, specifically focusing on the concepts of winning and losing positions.


Key Concepts

  1. Winning Position: A position where a player can guarantee a win regardless of the opponent's moves.
  2. Losing Position: A position where any move leaves the opponent in a winning position.

The game starts with 117 squares. A player can:

  • Remove 1 square.
  • Remove 2 consecutive squares.

This creates smaller sub-games for the opponent.


Step-by-Step Analysis

Base Cases:

  1. n=1n = 1: Only 1 square exists.
    • The first player removes it and wins. This is a winning position.
  2. n=2n = 2: Two squares exist.
    • The first player removes both (taking 2 consecutive squares) and wins. This is a winning position.
  3. n=3n = 3: Three squares exist.
    • The first player can:
      • Remove 1 square, leaving 2 squares (a winning position for the opponent).
      • Remove 2 squares, leaving 1 square (a winning position for the opponent).
    • Thus, n=3n = 3 is a losing position.

Generalizing the Pattern:

From the base cases, observe:

  • If the opponent is left with n=3n = 3, they are in a losing position.
  • Players aim to leave their opponent in a losing position.

Recursive Strategy:

  • For n>3n > 3, consider the current player’s moves:
    • Remove 1 square: Leaves n1n - 1.
    • Remove 2 squares: Leaves n2n - 2.

If either n1n - 1 or n2n - 2 is a losing position, the current position nn is a winning position.

Winning and Losing Positions:

Using the above logic, compute the sequence of positions:

  • n=1n = 1: Winning position.
  • n=2n = 2: Winning position.
  • n=3n = 3: Losing position.
  • n=4n = 4: Winning position (leave n=3n = 3 for the opponent).
  • n=5n = 5: Winning position (leave n=3n = 3 for the opponent).
  • n=6n = 6: Losing position (any move leaves n=4n = 4 or n=5n = 5, both winning for the opponent).
  • Continuing this pattern, n=3,6,9,12,n = 3, 6, 9, 12, \dots (multiples of 3) are losing positions.

Starting Position (n=117n = 117):

  • 117117 is a multiple of 3 (117=3×39117 = 3 \times 39).
  • Thus, n=117n = 117 is a losing position.

Conclusion

  • Player 1 starts in a losing position (n=117n = 117).
  • Player 2 has a winning strategy by always leaving a multiple of 3 for Player 1 after their turn.

Would you like a detailed explanation of the optimal moves for Player 2 or further questions on game theory concepts? Here are 5 related questions:

  1. How would the strategy change if the board had a different number of squares?
  2. What if players could remove 1, 2, or 3 consecutive squares?
  3. How can this concept be extended to boards with multiple rows?
  4. How are winning and losing positions related to the concept of "Nimbers" in combinatorial game theory?
  5. What algorithms can efficiently compute winning positions for larger games?

Tip: Understanding patterns in simple cases is key to solving combinatorial games.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Game Theory
Combinatorial Games
Winning and Losing Positions

Formulas

-

Theorems

Nim Game Strategy

Suitable Grade Level

Grades 9-12