On the projective dimension and the unmixed part of three cubics∗
نویسنده
چکیده
Let R be a polynomial ring over a field in an unspecified number of variables. We prove that if J ⊂ R is an ideal generated by three cubic forms, and the unmixed part of J contains a quadric, then the projective dimension of R/J is at most 4. To this end, we show that if K ⊂ R is a three-generated ideal of height two and L ⊂ R an ideal linked to the unmixed part of K, then the projective dimension of R/K is bounded above by the projective dimension of R/L plus one.
منابع مشابه
A bound on the projective dimension of three cubics
We show that given any polynomial ring R over a field and any ideal J ⊂ R which is generated by three cubic forms, the projective dimension of R/J is at most 36. We also settle the question of whether ideals generated by three cubic forms can have projective dimension greater than four, by constructing one with projective dimension equal to five.
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