Published in Volume XIX, 2009, pages 57-92

**Authors:** J.A. Bergstra and A. Ponse

### Abstract

We introduce an algebra of instruction sequences by presenting a semigroup C in which programs can be represented without directional bias: in terms of the next instruction to be executed, C has both forward and backward instructions and a C-expression can be interpreted starting from any instruction. We provide equations for thread extraction, i.e., C’s program semantics. Then we consider thread extraction compatible (anti-)homomorphisms and (anti-)automorphisms. Finally we discuss some expressiveness results.

Full Text (PDF)### References

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### Bibtex

@article{sacscuza:bergstra2009aisswia, title={An Instruction Sequence Semigroup with Involutive Anti-Automorphisms}, author={J.A. Bergstra and A. Ponse}, journal={Scientific Annals of Computer Science}, volume={19}, organization={``A.I. Cuza'' University, Iasi, Romania}, year={2009}, pages={57--92}, publisher={``A.I. Cuza'' University Press} }