“…There are a few taxonomies of mathematical software reliability models known at present [2,[19][20][21][22]. We believe that, from the applied perspective, it is convenient to use the classification relating to the objectives of software product/system testing stages [21], which allows 4 types of mathematical models to be singled out: [3,[21][22][23][24][25][26] which imply a strictly monotonous growth of software reliability. At present, this is not always consistent with current multiversion programming technologies.…”