If i = j, then it is the own-price elasticity of demand, otherwise magnitude is called the cross-price elasticity of demand.
 If i = j, then it is the own-price elasticity of demand
mnli hypothesis:  If i = j, then it is the own-price elasticity of demand premise: If i = j, then it is the own-price elasticity of demand, otherwise magnitude is called the cross-price elasticity of demand.