IN GEOMETRIC TERMS

year’s—but only up to a certain limit 0 i iv . Or he canmove in a somewhat northeasterly direction and betterhimself for both years at once, but again he can do thisonly up to a certain limit, 0 ” or O/".

CHART 35

The Opportunity (0) Line.

The boundary line 0/ Oi IV , made up of these limitingpoints may, of course, take various forms, but, for thepresent it will be assumed to be a curve concave towardthe origin. It is simply a geometric picture of the techni-cal limitations of an individual’s income in the two yearsconsidered, assuming, as always, all other years’ incomesto remain the same. It is the locus, or line, of options

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