PhD student of Dept. of Software Science Hendrik Maarand defends his PhD "Operational Semantics of Weak Sequential Composition" on Friday, Jun 26, 2020 at 10 AM in ICT-507 A/B (Akadeemia tee 15A) and via zoom.

A program is a collection of instructions to a computer for solving a certain problem. An important construct in programs is sequential composition: first do this and then that. Modern computer systems might not strictly adhere to such requirements. Instead, they only ensure that it seems as if everything is executed sequentially and in the given order. This is so to improve resource usage (for example, to make programs run faster). If we now take a multi-threaded program and execute it on a multi-core processor, then it is not enough any more to only have the impression that each thread in the program is executed sequentially. In other words, if we interpret sequential composition in a relaxed (or non-strict) manner, then the multi-threaded program may produce results that are not possible under the strict interpretation of sequential composition. An approach to formally describing the step-by-step execution of programs under such relaxed sequential composition is developed in this dissertation. Such descriptions provide a foundation for trustworthy analysis of programs.

Supervisor Lead Research Scientist Tarmo Uustalu (Tallinn University of Technology).

Opponents:

• Senior Lecturer Brijesh Dongol (Univ. of Surrey, UK)
• Professor Peter Thiemann (Univ of Freiburg, Germany).

The PhD thesis is available in Tallinn University of Technology digital library.