Gutev, Valentin; Nogura, Tsugunori(Universitat Politècnica de València, 2001-10-01)
[EN] Every selection f for the family F2(X) of at most two-point subsets of a set X naturally defines an order-like relation on X by if and only . In the present paper we study the relationship between and the possible ...
Gutev, Valentin; Nogura, Tsugunori(Universitat Politècnica de València, 2004-04-01)
[EN] The theory of hyperspaces has attracted the attention of many mathematicians who have found a large variety of its applications during the last decades. The theory has taken also its natural course and has yielded ...