1. of 12 12/04/2013CSOI: Communication as Coordination1 Communication as Coordination Madhu Sudan Microsoft, Cambridge, USA -

2. of 12 Overarching question Can intelligent devices communicate intelligently? Can intelligent devices communicate intelligently? Can printer explain to computer how to print on it? Can printer explain to computer how to print on it? Devices communicate for some reason – some functionality Devices communicate for some reason – some functionality Can it check for errors in functionality? Can it check for errors in functionality? It is interpreting the bits it receives correctly? It is interpreting the bits it receives correctly? Are messages it is sending being interpreted correctly? Are messages it is sending being interpreted correctly? Humans seem to manage: Humans seem to manage: How? Why? How? Why? 12/04/2013CSOI: Communication as Coordination2

3. of 12 Meaningful communication Meaning of bits Meaning of bits Bits sent/received are instructions Bits sent/received are instructions Definition of Understanding? Definition of Understanding? Devices understands if device follows instructions? Devices understands if device follows instructions? Not appropriate if instructions are not aligned with devices functionality! Not appropriate if instructions are not aligned with devices functionality! Need to know devices incentives and make sure they are compatible with instructions. Need to know devices incentives and make sure they are compatible with instructions. Mixes communication with Game Theory! Mixes communication with Game Theory! 12/04/2013CSOI: Communication as Coordination3

4. of 12 (Repeated) Coordination Game Single instance Single instance Alice and Bob have to simultaneously choose one of two actions, say {0,1} Alice and Bob have to simultaneously choose one of two actions, say {0,1} If both pick same action, both win. If both pick same action, both win. If they pick opposite actions, both lose. If they pick opposite actions, both lose. Main challenge: Dont know what the other person will choose when making our choice. Main challenge: Dont know what the other person will choose when making our choice. Repeated version: Repeated version: Play a sequence of games, using outcome of previous games to learn what the other player may do next. Play a sequence of games, using outcome of previous games to learn what the other player may do next. 12/04/2013CSOI: Communication as Coordination4

5. of 12 Our setting 12/04/2013CSOI: Communication as Coordination5

6. of 12 Motivation Models natural communication: Communication aims to settle some coordination like problem. Models natural communication: Communication aims to settle some coordination like problem. People making choices; would like to be compatible with neighbors. People making choices; would like to be compatible with neighbors. Other agents motivations not completely clear to us. Other agents motivations not completely clear to us. Communication attempts to explain our intent; but we still have a choice on how to assign meaning to the bits. Communication attempts to explain our intent; but we still have a choice on how to assign meaning to the bits. (Mis)coordination (in last round) signals our current understanding may be (in)correct. (Mis)coordination (in last round) signals our current understanding may be (in)correct. 12/04/2013CSOI: Communication as Coordination6

7. of 12 More formal definitions 12/04/2013CSOI: Communication as Coordination7

8. of 12 Coordinatable Strategies for Alice 12/04/2013CSOI: Communication as Coordination8

9. of 12 Theorems 12/04/2013CSOI: Communication as Coordination9

10. of 12 Theorems (contd.) 12/04/2013CSOI: Communication as Coordination10

11. of 12 Conclusions Game theory provides nice framework for casting questions about meaning of information. Game theory provides nice framework for casting questions about meaning of information. Using this framework, we can design communication strategies that learn to adapt and learn to serve functionality in a robust/changing environment. Using this framework, we can design communication strategies that learn to adapt and learn to serve functionality in a robust/changing environment. Need to make strategies active-passive Need to make strategies active-passive Should be capable of learning complex strategies and emulating them. Should be capable of learning complex strategies and emulating them. But should quickly revert to simple strategy that make it feasible for others to learn and emulate it. But should quickly revert to simple strategy that make it feasible for others to learn and emulate it. 12/04/2013CSOI: Communication as Coordination11

12. of 12 Thank You 12/04/2013CSOI: Communication as Coordination12