FUZZY SETS AND SYSTEMS, vol.427, pp.161-173, 2022 (SCI-Expanded)
Nullnorms with a zero element being at any point of a bounded lattice are an important generalization of triangular norms and triangular conorms. This paper obtains an equivalent characterization for the existence of idempotent nullnorms with the zero element a on any bounded lattice containing only two distinct elements incomparable with a. Furthermore, some basic properties for the bounded lattice containing only two distinct elements incomparable with a are presented. (c) 2020 Elsevier B.V. All rights reserved.