Reactive Control Improvisation

Daniel Fremont and Sanjit A. Seshia. Reactive Control Improvisation. In 30th International Conference on Computer Aided Verification (CAV), 2018.

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Abstract

Reactive synthesis is a paradigm for automatically building correct-by-construction systems that interact with an unknown or adversarial environment. We study how to do reactive synthesis when part of the specification of the system is that its behavior should be random. Randomness can be useful, for example, in a network protocol fuzz tester whose output should be varied, or a planner for a surveillance robot whose route should be unpredictable. However, existing reactive synthesis techniques do not provide a way to ensure random behavior while maintaining functional correctness. Towards this end, we generalize the recently-proposed framework of control improvisation (CI) to add reactivity. The resulting framework of reactive control improvisation provides a natural way to integrate a randomness requirement with the usual functional specifications of reactive synthesis over a finite window. We theoretically characterize when such problems are realizable, and give a general method for solving them. For specifications given by reachability or safety games or by deterministic finite automata, our method yields a polynomial-time synthesis algorithm. For various other types of specifications including temporal logic formulas, we obtain a polynomial-space algorithm and prove matching PSPACE-hardness results. We show that all of these randomized variants of reactive synthesis are no harder in a complexity-theoretic sense than ordinary reactive synthesis.

BibTeX

@inproceedings{fremont-cav18,
  author = {Daniel Fremont and Sanjit A. Seshia},
  title = {Reactive Control Improvisation},
  booktitle = {30th International Conference on Computer Aided Verification (CAV)},
  year = {2018},
  abstract = {Reactive synthesis is a paradigm for automatically building correct-by-construction 
systems that interact with an unknown or adversarial environment. 
We study how to do reactive synthesis when part of the specification of 
the system is that its behavior should be random. Randomness can be useful, for 
example, in a network protocol fuzz tester whose output should be varied, or a 
planner for a surveillance robot whose route should be unpredictable. However, 
existing reactive synthesis techniques do not provide a way to ensure random behavior 
while maintaining functional correctness. Towards this end, we generalize 
the recently-proposed framework of control improvisation (CI) to add reactivity. 
The resulting framework of reactive control improvisation provides a natural 
way to integrate a randomness requirement with the usual functional specifications 
of reactive synthesis over a finite window. We theoretically characterize 
when such problems are realizable, and give a general method for solving them. 
For specifications given by reachability or safety games or by deterministic finite 
automata, our method yields a polynomial-time synthesis algorithm. For various 
other types of specifications including temporal logic formulas, we obtain a 
polynomial-space algorithm and prove matching PSPACE-hardness results. We 
show that all of these randomized variants of reactive synthesis are no harder in 
a complexity-theoretic sense than ordinary reactive synthesis.},
}