STRATEGYMonths to result

Backward Reasoning

Think forward, reason backward

Problem it solves

unclear strategic direction

Best for

Sequential games with perfect information

Not ideal for

Simultaneous games or those with uncertainty

Overview

Why this framework exists

Backward reasoning is a method for solving sequential games by thinking forward to the endgame and reasoning backward to the current position. It involves analyzing the possible moves and their consequences, working backward from the final outcome to determine the optimal strategy. This approach is useful for games like chess, where the number of possible moves is finite and the outcome is determined by the moves of the players.

Core principles

3 total
  1. Think forward to the endgame and reason backward to the current position.
  2. Analyze the possible moves and their consequences.
  3. Work backward from the final outcome to determine the optimal strategy.

Steps

3 steps
  1. Define the game and its objectives
    Identify the game, its players, and the objectives of each player. Determine the possible moves and their consequences.
    Pro tipConsider the game tree, which represents all possible moves and their outcomes.
    WarningBe aware of the complexity of the game and the potential for uncertainty or randomness.
  2. Analyze the endgame
    Think forward to the endgame and determine the possible outcomes. Analyze the moves that lead to each outcome and their consequences.
    Pro tipConsider the concept of a 'winning' or 'losing' position, and how to achieve or avoid it.
    WarningBe aware of the potential for multiple equilibria or outcomes.
  3. Reason backward to the current position
    Work backward from the final outcome to determine the optimal strategy. Analyze the possible moves and their consequences at each step.
    Pro tipConsider the concept of a'subgame perfect equilibrium', which is a strategy that is optimal for all players at all nodes of the game tree.
    WarningBe aware of the potential for 'backward induction', where the optimal strategy is determined by the anticipated actions of other players.

Checklist

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Examples

2 cases
The 21-flags game

A game where two teams take turns removing flags, with the team taking the last flag winning. The optimal strategy can be determined using backward reasoning.

OutcomeThe team that uses backward reasoning can win the game, while the team that does not may lose.
Chess

A sequential game where the number of possible moves is finite and the outcome is determined by the moves of the players. Backward reasoning can be used to determine the optimal strategy.

OutcomeA player who uses backward reasoning can gain a strategic advantage over their opponent.

Common mistakes

3 traps
Failure to think forward
Not considering the possible outcomes and their consequences can lead to suboptimal decision making.
Failure to reason backward
Not working backward from the final outcome can lead to a failure to identify the optimal strategy.
Ignoring uncertainty or randomness
Failing to consider the potential for uncertainty or randomness can lead to suboptimal decision making.

Origin story

How this framework came to be

The concept of backward reasoning has its roots in game theory and has been applied to various fields, including economics, politics, and business. It is a powerful tool for strategic decision making, allowing individuals to anticipate and prepare for different scenarios and outcomes.

Source

Traced to primary
Source · BOOK
The Art of Strategy: A Game Theorist's Guide to Success in Business and Life
Dixit, Avinash K. · 2008
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