We study the interrelationships among concavity and weaker concavity notions of multi-variable functions, with or without differentiability. We show that modularity and homogeneity play central roles. Our characterizations offer illuminations on the n...
We study the interrelationships among concavity and weaker concavity notions of multi-variable functions, with or without differentiability. We show that modularity and homogeneity play central roles. Our characterizations offer illuminations on the nature of and the linkages among these function properties, and can be used in establishing economically meaningful results without appealing to derivatives.