On the topology of semi-algebraic functions on closed semi-algebraic sets
نویسندگان
چکیده
We consider a closed semi-algebraic set X ⊂ R and a C semi-algebraic function f : R → R such that f|X has a finite number of critical points. We relate the topology of X to the topology of the sets {f ∗ α}, where ∗ ∈ {≤,=,≥} and α ∈ R, and the indices of the critical points of f|X and −f|X . We also relate the topology of X to the topology of the links at infinity of the sets {f ∗ α} and the indices of these critical points. We give applications when X = R and when f is a generic linear function.
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