Sup-t-norm and inf-residuum are one type of relational product: Unifying framework and consequences

► The paper studies new framework generalizing residuated structures of truth degrees. ► In the framework, pairs of previously distinct concepts turn out one, more general concept. ► Two basic relational compositions, sup-t-norm and inf-residuum, are considered as an example. ► Two basic compositions are shown to be one type of composition in the framework.