Abstract
The starting point of this paper is a collection of properties of an
algorithm that have been distilled from the informal descriptions of
what an algorithm is that are given in standard works from the
mathematical and computer science literature.
Based on that, the notion of a proto-algorithm is introduced.
The thought is that algorithms are equivalence classes of
proto-algorithms under some equivalence relation.
Three equivalence relations are defined.
Two of them give bounds between which an appropriate equivalence
relation must lie.
The third lies in between these two and is likely an appropriate
equivalence relation.
A sound method is presented to prove, using an imperative process
algebra based on ACP, that this equivalence relation holds between two
proto-algorithms.