Public Tech Talk: “What is an EUTxO blockchain?”

  • Date Thursday, August 06, 2020  Time 9:30 AM
  • Speaker Jamie Gabbay, Researcher, Heriot-Watt University
  • Location Galois was pleased to host this tech talk via live-stream for the public. A video of the presentation can be found below.

The slides can be downloaded here.


The UTxO (unspent transaction output) model is the underlying data structure of Bitcoin, which has since been extended to the Extended UTxO model.

It exists in code, but what does it mean?  I will give a novel mathematical model based on some strikingly simple type equations which — for me at least — make it easier to see what is structurally going on.  I will describe how the equations can be used to obtain two further models, one which is more abstract and one which is more concrete:

  • A universal algebra axiomatisation, exhibiting Blockchain as an algebraic structure and so implying a general mathematics and specific testable properties against which to verify an EUTxO implementation,  and
  • An executable Haskell reference implementation.

A paper (accepted for publication), a journal paper (submitted), and Haskell code are online now.


Jamie Gabbay has been a researcher for twenty years in the logical foundations of mathematics and programming. He specialises in finding simplicity and precision by building models that nobody expected, based on connections that nobody thought would work. Recently, he has been thinking about blockchain.

Jamie is affiliated with Heriot-Watt University,

This talk was live-streamed and a recording is available by clicking the YouTube image at the top of this page.