Architectural patterns for user interfaces—MVC (1979), MVP (1996), MVVM (2005)—retain Model and View, leaving a single mediating role that inevitably takes on more than its intended perspective. We formalize this observation as the Equivalence Paradox: because Model and View remain invariant across all three patterns, each "third role" (Controller, Presenter, or ViewModel) tends to absorb responsibilities left explicit in the others, creating overloaded mediators. Kratochvil's MVPVM (2011) recognized four of these roles but dismissed the Controller as unnecessary in event-driven desktop environments. We propose MVCPVM (Model-View-Controller-Presenter-ViewModel) as a reference decomposition that makes all five roles explicit rather than collapsing three into one. By recognizing the five roles already implicit in practice, MVCPVM reframes debates over MVC, MVP, and MVVM as a question of explicit role distribution.
Jiun Kim (Sun,) studied this question.