但我发现v的书有个地方和别的不一样。那个substitution effect
wiki 还有其他的书定义是
hold the utility constant, a price change that alters the buget line. 所以buget line moves along the indifference curve.
但v的书里是这样定义的
rotate the buget line around the (x,y) , then the new buget line tengents another upper left indifference curve at (x1,y2) then the movement from (x y) to (x1, y1) defined as substitution effect??
为什么他们定义不一样顺便问下