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1 AI and Economics: The Dynamic Duo
Ariel ProcacciaCenter for Research on Computation and Society
Harvard SEAS
AI AND ECONOMICS
DYNAMIC
DUO
THE
2 AI and Economics: The Dynamic Duo
Theme
The interaction between AI and economics leads to new paradigms that can change the way we think about fundamental issues in AI and in economics
3 AI and Economics: The Dynamic Duo
The Game Plan
Game Theory
Social choice
Game Theory
AI
MAS
ML
UAI
Planning econ
KR
4 AI and Economics: The Dynamic Duo
Game Theory
“Game theory is a sort of umbrella ... for the rational side of social science, where ‘social’ is interpreted broadly” [Aumann 1987]
5 AI and Economics: The Dynamic Duo
Fun and Games
› Chess› Poker [Sandholm+]› Pool [Shoham+]
6 AI and Economics: The Dynamic Duo
AI and Game Theory
› GT offers: principles of rationality› AI offers: rational agents
[Rosenschein+Genesereth, IJCAI’85]»GTPlanning: Planning games
[Brafman+, IJCAI’09]
› AI also offers: new ways of thinking about rationality»UAIGT: Dynamic incentive mechanisms
[Parkes+]
7 AI and Economics: The Dynamic Duo
Small Example: Incentives in ML
AI
econ
Game Theory
Social choice
Game Theory
AI
Dekel+Fischer+P Incentive Compatible Regression Learning
JCSS 2010
MAS
ML
UAI
Planning
KR
ML
8 AI and Economics: The Dynamic Duo
Super Simplified model
› Input space X
› Each player i controls input point xi (public) and label yiR(private)
› Function class F of f:XR › Given reported labels, choose a
function fF
› Players want to minimize |f(xi)-yi|
› Designer wants to minimize i|f(xi)-yi|
9 AI and Economics: The Dynamic Duo
Let the Games Begin
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10 AI and Economics: The Dynamic Duo
If the Shoe Fits› Strategyproof mechanism = player never
gains from misreporting private information› Group strategyproof mechanism =
members of coalition cannot all gain from misreporting private information
› Theorem: Assuming one point per player and convex function class, best fit is group strategyproof» Follows immediately from known results for F =
constant functions (single peaked preferences)» Nontrivial for general convex function classes
11 AI and Economics: The Dynamic Duo
Simplified model
› Each player i controls input points xi1, xi2,... (public) and real labels yi1, yi2,... (private)
› Players want to minimize k|f(xik)-yik|
› Designer wants to minimize ik|f(xik)-yik|
12 AI and Economics: The Dynamic Duo
A Whole New Ball Game
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13 AI and Economics: The Dynamic Duo
Project-and-Fit
› Project-and-Fit: Project labels of each player onto closest fit, then fit with projected labels
› SP and gives quality guarantees for some function classes
14 AI and Economics: The Dynamic Duo
Project-and-Fit Illustrated
1
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1
1
15 AI and Economics: The Dynamic Duo
Slightly Simplified Model
› Each player has a distribution i over X and target function oi:XR
› Distributions sampled and labeled by players
› Players want to minimize expected error wrt i and oi
› Designer wants to minimize expected error wrt average player
› Theorem (informal): For any ,, given enough samples, results from previous model carry over up to with prob. 1-
16 AI and Economics: The Dynamic Duo
Late Motivation: Zara
› Optimizing distribution process of Zara [Caro+Gallien, OR 10]
› Regression learning is used to predict demand based on orders from store managers
› “... Zara’s inventory distribution process could be further improved in the future by introducing explicit incentives for the stores to contribute accurate forecasts.”
17 AI and Economics: The Dynamic Duo
Can GT Enable AI?
› Classic AI seeks to design intelligent robots/agents
› Some of modern AI studies agent societies
› GT distills rationality› Rationality is perceived as intelligence› Game-theoretic MAS may be
perceived as intelligent› GT enables AI on the multiagent level!
18 AI and Economics: The Dynamic Duo
The Game Plan
Game Theory
Social choiceA
I
econSocial choice
MAS
ML
UAI
Planning
KR
19 AI and Economics: The Dynamic Duo
Social Choice Theory
Social choice theory is a theoretical framework for measuring individual interests, values, or welfares as an aggregate towards collective decision
20 AI and Economics: The Dynamic Duo
AI and Social Choice
› CS + SC = computational social choice
› SC offers: preference aggregation»SCMAS: Restricted communication
[Caragiannis+P, AAAI’10]
› AI offers: complex preferences»KRSC: Voting on multiattribute
domains with CP-nets [Lang, IJCAI’07]
21 AI and Economics: The Dynamic Duo
The basics
› Set of n voters: {1,...,n}› Voters are honest!› Set of m alternatives: {a,b,c,...}› Each voter ranks the alternatives› Preference profile = collection of rankings› Voting rule selects alternative given profile
» Plurality: each voter awards one point to top alternative
» Borda count: each voter awards m-k points to alternative ranked k’th
22 AI and Economics: The Dynamic Duo
Majority Consistency
Voter 1
a
b
c
d
Voter 2
a
c
d
Voter 3
c
d
a
b
b
23 AI and Economics: The Dynamic Duo
Big Example:Dynamic Social Choice
Game Theory
Social choiceA
I
econSocial choiceA
I
Parkes+P Dynamic Social Choice
Working paper
MAS
ML
UAI
Planning
KR
UAI
24 AI and Economics: The Dynamic Duo
Motivation: MoveOn
› Online public policy advocacy group
› 5 million members, handful of staffers
› Causes stem from preferences of members
› Short time frames› Acting on a cause changes
preferences, affecting next cause
25 AI and Economics: The Dynamic Duo
Social Choice MDPsba
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Voters 1+2 Voter 3
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26 AI and Economics: The Dynamic Duo
Rewards and Policies
› MDP components: states, actions, transitions, rewards
› Reward function specifies (designer’s) reward for each state and action» Favorite alternative» Social consensus
› (Deterministic stationary) policy selects action/alternative at each state/profile
27 AI and Economics: The Dynamic Duo
Take-Home Message
“A policy in a social choice MDP is a voting rule”
28 AI and Economics: The Dynamic Duo
Rewards and Policies
› MDP components: states, actions, transitions, rewards
› Reward function specifies (center’s) reward for each state and action» Favorite alternative» Social consensus
› (Deterministic stationary) policy selects action/alternative at each state/profile
› Maximize infinite sum of discounted rewards...
› ... subject to social choice constraints!
29 AI and Economics: The Dynamic Duo
½
½1
Exploiting Symmetries
› In general finding an optimal policy is easy
› First obstacle: state space is exponential in n and m
› Assume constant m and constant #transition models
› Contract symmetric states [Dean+Givan AAAI’97]
ba
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30 AI and Economics: The Dynamic Duo
Social Choice Constraints
› Second obstacle: constraints»Literature falls short
› Theorem: Assume a constant m and constant #transition models. Can compute an optimal policy subject to axiom in poly time in n»axiom {majority consistency,
ontoness,...}
› Example: Ontoness
31 AI and Economics: The Dynamic Duo
Algorithm by Animation
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32 AI and Economics: The Dynamic Duo
Implementation
› Challenges»Developing transition models»Practical heuristics
› Extend to dynamic voters and alternatives
33 AI and Economics: The Dynamic Duo
CS and SC: Yin and Yang
34 AI and Economics: The Dynamic Duo
A New Hope
› Classic SC is rife with impossibilities› Computational social choice is
constructive and positive› AI is a testbed for principles of SC
»Via MAS»Via human computation
› Does classic SC literature have “operational value”?
35 AI and Economics: The Dynamic Duo
back to theme
The interaction between AI and economics leads to new paradigms that can change the way we think about fundamental issues in AI and in economics
36 AI and Economics: The Dynamic Duo
Research Overview
› AI + Computational GT and SC› Fair division› Combinatorial optimization and
approximation algorithms› Crowdsourcing and human
computation
37 AI and Economics: The Dynamic Duo
The End
Thank You!
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