// end existential delay
private void SetDelay(ISymValue sv, DefAssignLattice.Delay delay) {
DefAssignLattice.AVal aval = (DefAssignLattice.AVal)this.egraph[sv];
this.egraph[sv] = aval.SameButWith(delay);
}
private void SetAssigned(Variable v, DefAssignLattice.AVal aval) {
if (v == null) return;
SetAssignedStatus(v);
ISymValue sv = this.egraph[v];
// assignment makes value unknown
this.egraph.Eliminate(ValueOf, sv);
this.egraph[sv] = aval;
}