To je jedna od "teorija igara", ekonomska teorija, u ovom delu odnosi se na maksimiziranje profita.Hotellingova teorija igara u uslovima oligopola. Radi se o grafiku profitne funkcije, tj.

http://www.chass.utoronto.ca/~osborne/MathTutorial/MEE.HTM

"Why is the result called the envelope theorem? The American Heritage Dictionary (3ed) gives one meaning of "envelope" to be "A curve or surface that is tangent to every one of a family of curves or surfaces". In the following figure, each black curve is the graph of f as a function of r for a fixed values of x. (Only a few values of x are considered; one can construct as many as one wishes.) Each of these graphs shows how f changes as r changes, for a given value of x. To find the solution of the maximization problem for any given value of r, we find the highest function for that value of r. For example, for r = r˘, the highest function is the one colored blue. The graph of the value function f * is the locus of these highest points; it is the envelope of the graphs for each given value of x. From the figure, the envelope theorem is apparent: the slope of the envelope at any given value of r is the slope of the graph of f (x*(r), r). (For example, the slope of the envelope at r˘ is the slope of the blue curve at r˘.)