In this note we prove that the unique concave t-norm is Minimum and, among the class of triangular functions that have the family of unit step-functions as idempotent elements, the unique concave triangular function is piM.
@article{urn:eudml:doc:38909, title = {Sobre la concavidad de t-normas y de funciones triangulares.}, journal = {Stochastica}, volume = {8}, year = {1984}, pages = {91-95}, zbl = {0567.26010}, mrnumber = {MR0780142}, language = {es}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:38909} }
Agell, Núria. Sobre la concavidad de t-normas y de funciones triangulares.. Stochastica, Tome 8 (1984) pp. 91-95. http://gdmltest.u-ga.fr/item/urn:eudml:doc:38909/