Axiom is  a general purpose Computer Algebra system. It is useful for research and development of mathematical algorithms. It defines a strongly typed, mathematically correct type hierarchy. It has a programming language and a built-in compiler.
Polybutylene is simply a type of plumbing material that was manufactured between the late 70's and early 90's. It is thought that it was installed in over 6 million homes during that time period.
Definition [Suggest Change] Performance-based payments (PBPs) are a customary method of contract financing that may be available under fixed-price contracts, except for contracts awarded using Sealed Bidding procedures.