Blowing down
From Infogalactic: the planetary knowledge core
In mathematics, blowing down is a type of geometric modification in algebraic geometry.[1] It is the inverse operation of blowing up.[2]
On an algebraic surface, blowing down a curve lying on the surface is a typical effect of a birational transformation. The curves that blow down, to a non-singular point, are of a special kind: they are rational curves, with self-intersection number −1.
References
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