In the paper the entropy of L-R fuzzy numbers is studied. It is shown that
for a given norm function, the computation of the entropy of L-R fuzzy numb
ers reduces to using a simple formula which depends only on the spreads and
shape functions of incoming numbers. In detail the entropy of T-M-sums and
T-M-products of L-R fuzzy numbers is investigated. It is shown that the re
sulting entropy can be computed only by means of the entropy of incoming fu
zzy numbers or by means of their parameters without the computation of memb
ership functions of corresponding sums or products. Moreover, the results f
or some other t-norm-based sums and products are derived. Several examples
are included.