Topics on perfect ideals of codimension two
Monomial ideals, plane reduced points, special fiber, perfect ideal of codimension two, Rees algebra, Cohen–Macaulay.
In this work, we are interested in perfect ideals $I$ of codimension two in a polynomial ring $R$ over a field of characteristic zero. The overall interest is on the homological nature of the main algebras related to the HilbertBurch syzygy matrix associated to $I$, in particular on the Cohen-Macaulay property of the Rees algebra and the special fiber of $I$. We develop this study in three contexts: monomial ideals, ideals defined by the $2$minors of homogeneous $3\times2$ matrices, and the defining ideal of a finite set of reduced points in projective $2$-space. In addition, we investigate geometric aspects related to these ideals, focusing on how their algebraic properties are reflected in the associated rational maps.