Gorman’s theory of demand is extended comprehensively to incomplete systems. The incomplete systems approach dramatically increases this class of models. The separate roles of symmetry and adding up are identified in the rank and the functional form of this class of models. We show that...

Gorman's class of Engel curve demand models is extended to incomplete demand systems. The Gorman class of aggregable incomplete demand systems admits any transformation of deflated income. A maximum rank of three for the demand equations is a corollary of Slutsky symmetry. Models of incomplete...

Gorman Engel curves are extended to incomplete systems. The roles of Slutsky symmetry and homogeneity/adding up are isolated in the rank and functional form restrictions for Gorman systems. Symmetry determines the rank condition. The maximum rank is three for incomplete and complete systems....