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.
How to Use S-Traps or P-Traps in Plumbing. To be legal, a trap must run horizontally on the outflow side. Fixture traps protect your home from sanitation issues involving drains that tie into the sewer or a home septic system. A trap is length of pipe with a curve that bottoms out with a P or S shape. The curve holds a pool of water that seals out gases rising from the sewer side of the pipe.