The constrained shortest common supersequence problem

Shortest common supersequence and longest common subsequence are two widely used measures to compare sequences in different fields, from AI planning to Bioinformatics. Inspired by recently proposed variants of these two measures, we introduce a new version of the shortest common supersequence problem, where the solution is required to satisfy a given constraint on the number of occurrences of each symbol. First, we investigate the computational and approximation complexity of the problem, then we give a 32-approximation algorithm. Finally, we investigate the parameterized complexity of the problem, and we present a fixed-parameter algorithm.