We consider a class of functions satisfying the gross-substitution property (GS-functions). We show that GS-functions are concave functions whose parquets are constributed by quasi-polymatroids. The class of conjugate functions to GS-functions turns out to be the class of polyhedral supermodular...

We revisit the issue of existence of equilibrium in economies with indivisible goods and money, in which agents may trade many units of items. In [5] it was shown that the existence issue is related to discrete convexity. Classes of discrete convexity are characterized by the unimodularity of...