Blockchains that support a general contract layer (e.g., Ethereum) export the functionality of a general-purpose, ownerless, and open-access computer that can enforce property rights for digital data. How is such functionality implemented? Using a lot of extremely cool computer science ideas! And like everywhere else in computer science, theory plays an undeniable role in the understanding and advancement of this technology.

In this talk, Tim Roughgarden will highlight three examples (among many):

• Possibility and impossibility results for permissionless consensus (i.e., implementing an "ownerless" computer).
• Incentive-compatible transaction fee mechanism design (part of implementing an "open-access" computer).
• Succinct proofs of computation (for boosting the computer's power by piggybacking on off-chain computation).

Parts of this talk are based on joint work with Andrew Lewis-Pye.

Tim Roughgarden is a Professor in the Computer Science Department at Columbia University. Prior to joining Columbia, he spent 15 years on the computer science faculty at Stanford, following a PhD at Cornell and a postdoc at UC Berkeley. He works on the boundary of computer science and economics, and on the design, analysis, applications, and limitations of algorithms.