Uninorm; Triangular Norm; Triangular Conorm, Aggregation Function; Neutral element; Bounded lattice

In this paper, we propose a characterization of uninorms on a general bounded lattice L by means of a sixtuple (T; S;H1;H2;H3;H4), where T is a triangular norm, S is a triangular conorm, and H1, H2, H3 and H4 are binary aggregation functions on L: Observe that in the case when L is a chain, it is enough to consider a triple (T; S;H). An example of a proper uninorm which is also a proper nullnorm is also shown (note that this cannot happen if we consider operations acting on a chain). Two general constructions of uninorms on L are added, fixing (S;H1;H2;H3;H4) and letting T ( fixing (T;H1;H2;H3;H4) and letting S) to be free up to a relation to the chosen neutral element e.