# Evaluation Through Conflict Martin Zinkevich Yahoo! Inc.

## Presentation on theme: "Evaluation Through Conflict Martin Zinkevich Yahoo! Inc."— Presentation transcript:

Evaluation Through Conflict Martin Zinkevich Yahoo! Inc. http://martin.zinkevich.org/lemonade

Who was I Worked with U Alberta Computer Poker Research Group – Designed Counterfactual Regret Algorithm – Theory behind DIVAT Worked on AAAI Computer Poker Competition – 2006 as lead programmer, 2007 as chair Work used in Man Vs Machine

Who am I Run the Lemonade Stand Game Competition Work with Yahoo Anti-Abuse Team

AAAI Computer Poker Competition 5 years running Now the ANNUAL Computer Poker Competition Latest-11 universities et al

Competitions: Science vs Entertainment

AAAI Computer Poker Competition May The Best Program Win! And Win Again IF WE PLAYED AGAIN!

All Combinations 7,-710,-10 -7,75,-5 -10,10-5,5

OK, But Who Won? Online: Maximize total winnings Equilibrium: Maximize number of people I can win money from (or don’t lose against)

Why a New Competition? Computing Equilibria ✓ Choosing Equilibria ?

Bach or Stravinsky 2,12,10,00,0 0,00,01,21,2

Big Question: How Do (or Would) People Get to Nash Equilibria?

Solvable Games \$

Unsolvable Games ∞ \$ ?

Solving the Unsolvable In current competitions, people are often applying techniques that are effective in solvable games, even when the game is not solvable. In what competitions is it useless to approximate the game as solvable?

Axelrod’s Iterated Prisoner’s Dilemma A competition between many competitors. One entry: tit-for-tat (Anatol Rapaport) – Nice (initially) – Retaliating – Forgiving – Non-envious Learned that cooperation has value, but: – Cooperate with whom? – How do we cooperate?

What Is The Lemonade Stand Game? Every round for 100 rounds: – each person selects an action privately – then, the actions are revealed The score of a player is the distance clockwise to the next player plus the distance counterclockwise.

Key Observations A constant-sum game between 3 players. – For every gain, someone has to lose. Possibilities For Cooperation – Opposite sides of the circle, “sandwiching” Not a “Solvable Game” (Nash, 1951) – Playing equilibrium strategies is not advisable Easy To Set “Table Image” – The constant strategy often evokes cooperative behavior Existing Techniques Fail – Experts algorithms lose to constant strategy Strategy #1: Play Constant Strategy #2: Play Opposite Strategy #3: Sandwich

Competition Structure Every set of three players played 100 rounds 180 times (1.5 million rounds total) Highest Total Score Wins Mean, Standard Error can be calculated

Competitors 28 players, 9 teams – University of Southampton/Imperial College London (Soton) – Yahoo! Inc. (Pujara) – Rutgers University (RL3) – Brown University (Brown) – Carnegie Mellon (2 teams-Waugh, ACTR) – University of Michigan (FrozenPontiac) – Princeton University (Schapire) – (Greg Kuhlmann)

Competition Results Competitor Score Per Round

Results Competitor Score Per Round-8 Modified ConstantUniformly Random

Restricting to Top 6 Competitor Score Per Round-8

Restricting to Top 4

Teach Simply! EQUILIBRIUM FREE =

Learn = = = ?

= = 10 7

The High Level Phenomenal Intelligence: the observed behavior used by a set of people at a point in time for some task.

Lofty Goals Phenomenal Intelligence: the observed behavior used by a set of people at a point in time for some task. behavior: a fully specified strategy. used: actually leveraged

Practical Concessions Phenomenal Intelligence: the observed behavior used by a set of people at a point in time for some task. Not any intelligent agent Not any time (people change) Not any task (context matters)