Let $X$ be a smooth projective variety over $\mathbb{C}$, $NS(X)$ be its Neron-Severi group, i.e., the abelian group generated by divisors modulo algebraic equivalence, and $NS_{tor}(X)$ be the torsion subgroup of $NS(X)$. Could anyone help me to understand why is $NS(X)$ a birational invarint?
2026-02-22 18:14:53.1771784093
Why is the torsion subgroup of the Neron Severi group a birational invariant?
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