Committing to User Choices in Mixed Initiative CSPs

In a mixed initiative system for solving a constraint satisfaction problem (CSP), both the user and the system make choices in trying to find a solution. These choices typically involve deciding what values to assign to variables. A desirable property in mixed initiative systems is that they commit to user choices: the user assignments should be retained as long as there is a complete solution containing those assignments. This paper shows that several backtracking algorithms, that are typically used to solve constraint satisfaction problems, do not commit to user choices. We also describe a slight modification of Ginsberg's dynamic backtracking algorithm [4] that does commit to user choices. 1 Introduction Many problems can be viewed as constraint satisfaction problems (CSPs). A CSP consists of a set of variables, each of which is associated with a domain of values, and a set of constraints on subsets of the variables. A solution to a CSP is an assignment of values to variables such ..