THE NOAHS-ARK PROBLEM

This paper is about the economic theory of biodiversity presentation. A cost-effectiveness methodology is constructed, which results in a pa rticular formula that can be used as a criterion to rank projects. The ranking criterion is sufficiently operational to be useful in suggest ing what to look at when determining actual conservation priorities am ong endangered species. At the same time, the formula is firmly rooted in a mathematically rigorous optimization framework, so that its theo retical underpinnings are clear. The underlying model, called the ''No ah's Ark Problem,'' is intended to be a kind of canonical form that ho nes down to its analytical essence the problem of best preserving dive rsity under a limited budget constraint.