Shipley Company12 is designing a new photoresist, which is a chemical coating used in the photoengraving of silicon chips. Important characteristics of photoresists are i = 1, high flow

(liquefication) temperature; i = 2, low minimum line-space resolution; i = 3, retention of unexposed areas when exposed circuits are developed away at least b3; i = 4, photospeed (minimum exposure time to create an image) between b4 and b4; and i = 5, exposure energy requirements between b5 and b5. Ingredients j = 1,

c, 24 produce highly nonlinear effects on these five important characteristics. However, designed experiments have demonstrated that the effects can be assumed linear within ingredient quantity ranges [lj, uj] under consideration. Between these limits, each additional unit of ingredient j adds ai, j to characteristic i of the photoresist.

(a) Formulate a 2-objective LP model to choose the best composition for both flow temperature and line-space resolution.

(b) Explain the meaning of an efficient point solution to your model in part (a), and describe how one could be computed.