Physical oracles: Measurement, complexity and cyber-physical systems

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• Edwin Beggs (Maths, Swansea University)
• Friday 23 March 2018, 11:00-12:00
• Computer Science, The Sloman Lounge (UG).

If you have a question about this talk, please contact Paul Taylor.

Turing’s mythological 1939 idea of oracle postulated a device that was not a Turing machine and lay outside the formal idea of algorithms. The oracle is a source of information for an algorithm. Suppose that the oracle is a physical process or experiment – a ‘physical oracle’. As a physical process, this oracle is subject to errors and time delays, and further can be analysed using one or more competing

physical theories that allow us to understand its behaviour.

We can look at interactions between algorithms and the physical world in two ways: (i) a physical oracle assists a computation (e.g. an analogue computer), or (ii) a computer controls an experiment. We can draw conclusions for both the theories of measurement and complexity. Reasonable assumptions suggest a limit of the non-uniform complexity class BPP //log* for an algorithm assisted by a physical oracle.

Cyber-physical systems can be viewed as consisting of algorithms communicating with a mixture of other algorithms and physical oracles. We consider the consequences of the limitations on physical oracles on cyber-physical systems, and in particular the idea of splitting physical systems into modes for the purposes of control theory.

This talk is part of the Theoretical computer science seminar series.

This talk is included in these lists:

• Computer Science Departmental Series
• Computer Science Distinguished Seminars
• Computer Science, The Sloman Lounge (UG)
• Theoretical computer science seminar
• computer sience

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