许宝(马条)
<正> The question of two-fold repeated limits in connection with afunction of two real variables has boon treated by Priugsheim,London,Hobson,Townsend,and Osgood.According tothe definition given by the first three writers,the repeated limitlira Jim f(x,y) may exist without the existence of lira f(x,y).Weshall,however,use the simpler definition,so that for the existenceof a certain iterated limit all the iterated limits of lower order mustexist.Assuming the existence of the two limits lira lira f(x,y)and