David,


>>
> I think a similar argument "at the margins" would show that even if the
> task were specified as maximal value with a budget, simply ordering by the
> value/price and buying until the cumsum of the price was greater than budget
> would solve the alternate statement of the problem. I suppose there might be
> situations where there were marginal choices of buying two books whose
> value/price was less than marginally maximal because two other marginally
> maximal choices would break the budget. This sounds like a homework problem
> and I don't see any student effort yet. Search terms include: "decision
> analysis" , "cost-benefit analysis", or "utility theory".
>

Hopefully,  my response to Ben will clarify my question, and why I am asking
it.  At the moment (and that may change) I'm not specifically interested in
how you do it R, just as to whether there is a package aimed at this kind of
Cost Benefit analysis.

Graham

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