Patent ID: 7890896

Claim:
A computer-implemented method for determining whether a first and a second design are functionally different, comprising: producing, by at least one computer, a first data structure from the first design, representative of a first set of minterms, wherein the first set of minterms defines a functionality of the first design; producing, by at least one computer, a second data structure from the second design, representative of a second set of minterms, wherein the second set of minterms defines a functionality of the second design; assigning, by at least one computer, a first weighted minterm count to the first data structure, which involves evaluating expressions in which weights are assigned to the first set of minterms with a variable level weighting function, a minterm level weighting function and a design level weighting function, wherein the variable level weighting function assigns a weight to a variable of a minterm, wherein the minterm level weighting function assigns a weight to a minterm based at least on weights assigned to variables of the minterm, and wherein the design level weighting function assigns a weight to a combinational sub-design; assigning, by at least one computer, a second weighted minterm count to the second data structure, which involves evaluating expressions in which weights are assigned to the second set of minterms with the variable level weighting function, the minterm level weighting function and the design level weighting function; and deciding, by at least one computer, the first and second designs are functionally different in response to determining that the first weighted minterm count is not within a first tolerance of the second weighted minterm count.