An incremental verification method includes eliminating verification
constraints from a first netlist and using the resulting netlist to
create a constraint-free composite netlist suitable for determining
equivalence between the first netlist and a second netlist of a design.
Eliminating a constraint from a netlist may include adding a modified
constraint net where the modified constraint net is FALSE for all cycles
after any cycle in which the original constraint is FALSE. The method may
include, instead of eliminating constraints, determining that the
verification result is a target-not-asserted result and that the second
netlist constraints are a superset of the first netlist constraints or
that the verification result is a target-asserted result and that the
first netlist constraints are a superset of the second netlist
constraints. In either case, the method may include creating the
composite netlist by importing all of the original constraints into the
composite netlist.