Definition:Concatenation of URM Programs

Let $$P$$ and $$Q$$ be URM programs.

The concatenation of $$P$$ and $$Q$$ is denoted $$P * Q$$.

It consists of program $$P$$ followed immediately by program $$Q$$.

If $$P$$ and $$Q$$ compute particular functions, then it is usually necessary to make modifications to either $$P$$ or $$Q$$, or both, to make sure that the concatenated program continues to compute a function.

The simplest concatenation is illustrated in Composition of One-Variable URM Computable Functions.