Improving the Performance of Interactive Configuration with Regular String Constraints

A generalization of the problem of interactive configuration has previously been presented in [1]. This generalization utilized decomposition to extend the standard finite domain interactive configuration framework to deal with unbounded string variables and provided features such as prefix auto-completion. In this paper we present several significant improvements to the core data structures and algorithms in [1] as well as the first implementation of an interactive configurator on string variables. The primary improvement is obtained by replacing the binary decomposition model with a finite domain model. We then describe an optimization for this model which allows us to replace the use of costly conjunctions with simple restrict operations during synchronization between decomposed constraints. In addition we describe how to improve the performance of the auto-complete operation, by using projection on relevant variables to significantly reduce the size of the data structures involved. We empirically verify the critical significance of these improvements using our own implementation of a string variable based configurator on real-world example data.