Small improvement that replaces the use patricia trees to store variables (xvars and yvars) that are not required to be sorted. This occurs in join and widening and reduces unnecessary overhead.
Small improvement that replaces the use patricia trees to store variables (xvars and yvars) that are not required to be sorted. This occurs in join and widening and reduces unnecessary overhead.

seahorn/crab,caballa/crab,seahorn/crab