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发帖数: 17 | 1 P23 chapter1 3.18 (b)怎么做？
Projectively Normal Varieties
A projective variety Y(P^n的子集） is projectively normal (with respect to
the given embending ) if its homogeneous coordinate ring S(Y) is
integrally closed.
(b)let Y be the twisted quartic curve in P^3 given parametrically by
(x,y,z,w)=(t^4,t^3*u,t*u^3,u^4). Then Y is normal but not projectively
normal.
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