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Strategies

Tit for Tat

Cooperates first, then copies the opponent's previous move.

Pavlov

Repeats successful behavior and switches after an unfavorable result.

Random

Chooses cooperate or defect using the match's seeded random generator.

Always Cooperate

Cooperates every round.

Always Defect

Defects every round.

Grim Trigger

Cooperates until the first opponent defection, then defects forever.

Tit for Two Tats

Defects only after two consecutive opponent defections.

Two Tits for Tat

Defects if either of the last two opponent moves was a defection.

Generous Tit for Tat

Copies the opponent, with a 10% chance of forgiving a defection.

Suspicious Tit for Tat

Defects first, then copies the opponent's previous move.

Gradual

Counts all opponent defections; when idle, punishes a new defection for that many rounds, then cooperates twice.

Naive Prober

Tit for Tat with a 10% chance of defecting instead of cooperating.

Remorseful Prober

Probes like Naive Prober, but cooperates if the opponent defects immediately after a probe.

Hard Tit for Tat

Defects if any of the last three opponent moves was a defection.

Soft Majority

Cooperates first and when opponent cooperations equal or outnumber defections.

Hard Majority

Cooperates only when opponent cooperations strictly outnumber defections; defects first.

Adaptive

Plays six cooperations then five defections; thereafter picks the move with the higher average payoff, cooperating on ties.

Random Cooperate Bias

Independently cooperates with 70% probability each round.

Random Defect Bias

Independently cooperates with 30% probability each round.

Alternate

Starts with cooperation, then switches its own move every round (Always Switch).

Detective

Opens C, D, C, C; uses Tit for Tat if the opponent defected in those four rounds, otherwise defects forever.

Handshake

Opens C, D; then cooperates forever with opponents matching that opening and defects against others.

Contrite Tit for Tat

Copies the opponent; after an accidental own defection, cooperates until mutual cooperation returns. Without noise, behaves like Tit for Tat.

Rounds per match

Matches per pairing

Seed

Include self-play

Payoff settings

Points earned for each outcome. The same values apply to every match.

Temptation

Reward

Punishment

Sucker

Temptation: defect against cooperation. Reward: both cooperate. Punishment: both defect. Sucker: cooperate against defection.

253 matches · 25,300 total rounds (100,000 max)

Results

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