elastic supply:when the quantity supplied changes by a greater percentage than the change in price (1<PES<infinity)
inelastic supply:when the quantity supplied changes by a smaller percentage than the change in price.(1<PES<1)
unit PES:when a change in price causs an equal percentage change in quantity supplied (PES=1)
perfectly elastic supply:when a change in price causes a complete change in quantity supplied (PES=infinity)
perfectly inelastic supply:when a change in price has no effect on the quantity supplied.(PES=0)