 I.e., if the price of "Y" increases, then the demand for "X" either remains constant or increases, but does "not" decrease.A utility function is called GS if, according to this utility function, all pairs of different goods are GS.With a GS utility function, if an agent has a demand set at a given price vector, and the prices of some items increase, then the agent has a demand set which includes all the items whose price remained constant.