 Another, non-idempotent, conjunction \(\&amp;\) is typically added to account for the intuition that applying a partially true hypothesis twice might lead to a different degree of truth than using it only once. Such a conjunction is usually interpreted by a binary operation on \([0,1]\), which is not necessarily idempotent, but still associative, commutative, non-decreasing in both arguments and has \(1\) as neutral element. These operations are called t-norms (triangular norms) and their mathematical properties have been thoroughly studied (see Klement, Mesiar, &amp; Pap 2000). Prominent examples of t-norms are the already mentioned function \(\min\), the standard product \(\cdot\) of real numbers, and the Łukasiewicz t-norm: \(x *_{Ł} y=\max\{x+y-1,0\}\). These three t-norms are actually continuous functions and any other continuous t-norm can be described as an ordinal sum of these three basic ones (Ling 1965; Mostert &amp; Shields 1957).