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.
Knowing the types of plumbing pipes in your home lets you take steps to prevent leaks, flooding, and potential health hazards. Polybutylene is prone to breakage, but it can be replaced with PEX, as it was here. Nothing lasts forever, and that includes the plumbing pipes in your home. Fortunately, the majority of pipe materials perform well for decades. However, when that lifespan is reached, pipes may start to leak.