Semialgebraic space
In mathematics, especially in real algebraic geometry, a semialgebraic space is a space which is locally isomorphic to a semialgebraic set.
Definition
Let U be an open subset of Rn for some n. A semialgebraic function on U is defined to be a continuous real-valued function on U whose restriction to any semialgebraic set contained in U has a graph which is a semialgebraic subset of the product space Rn×R. This endows Rn with a sheaf [math]\displaystyle{ \mathcal{O}_{\mathbf{R}^n} }[/math] of semialgebraic functions.
(For example, any polynomial mapping between semialgebraic sets is a semialgebraic function, as is the maximum of two semialgebraic functions.)
A semialgebraic space is a locally ringed space [math]\displaystyle{ (X, \mathcal{O}_X) }[/math] which is locally isomorphic to Rn with its sheaf of semialgebraic functions.
See also
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