In modern fuzzy logic theory (see Refs. [2~12]), t-norm
based logic usually refers to residuated systems of fuzzy
logic with t-norm based semantics, i.e. where the
conjunction connective is interpreted by a t-norm and the
implication operator by its residuum. Hajek [2] introduces
a logic system, named BL, which is the logic of all
continuous t-norms and of their residua. Esteva et al. in
Ref. [3] propose monoidal t-norm based logic (MTL), and
conjecture that MTL is the logic of left-continuous t-norms
and of their residuals. This conjecture was shown to be
true in Ref. [4]. The fuzzy logic system the logic of
nilpotent minimum (NM) is an important schematic
extension of MTL, and further studies in many literatures
(see Refs. [5–6])