The original Rete algorithm, which Forgy developed with DOD money, belongs to the public domain. You might notice that WaltzDB-16 takes longer to run on Rete-NT than on Rete-2.

The Rete algorithm was developed in the late 1970s by Dr. Charles Forgy and, at that time, increased the performance of the standard LISP inference engines by as much as 3,000 times over an engine ...