SUBSTITUTION AND ARBITRAGE POSSIBILITIES. A number of the Ivies have been competing to spend their endowments as tuition waivers to people of modest means. Robert VerBruggen of Phi Beta Cons suggests that the positional arms race will change as the tuition waivers induce more applicants at what he characterizes as a "fixed number of slots" at the "top schools." In that competition is an opportunity for the land-grants and mid-majors to note that they are in the same business as Harvard and Brown, and as capable of delivering the same educational experience. Mr VerBruggen's remark that the competition has to work down the "prestige chain" suggests that parents and students -- perhaps some of the well-to-do ones who will compare in-state tuitions at Madison or Urbana or DeKalb with full fare at the Ivies -- might lobby for greater intellectual challenges. We shall see.