Lemma 41.46.2. In the situation of Definition 41.45.4 assume $P_ p(Z \to X, E)$, resp. $c_ p(Z \to X, E)$ is defined. Let $Y \to X$ be locally of finite type and $c \in A^*(Y \to X)$. Then

$P_ p(Z \to X, E) \circ c = c \circ P_ p(Z \to X, E),$

respectively

$c_ p(Z \to X, E) \circ c = c \circ c_ p(Z \to X, E)$

in $A^*(Y \times _ X Z \to X)$.

Proof. This follows from Lemma 41.44.4. Namely, our assumptions say $E$ is represented to a bounded complex $\mathcal{E}^\bullet$ of finite locally free $\mathcal{O}_ X$-modules. Let

$b : W \to \mathbf{P}^1_ X \quad \text{and}\quad \mathcal{Q}^\bullet$

be the blowing up and complex of $\mathcal{O}_ W$-modules constructed in More on Flatness, Section 37.44. Let $T \subset W_\infty$ be the closed subscheme whose existence is averted in More on Flatness, Lemma 37.44.1. Let $T' \subset T$ be the open and closed subscheme such that $\mathcal{Q}_ i^\bullet |_{T'_ i}$ is zero, resp. isomorphic to a finite locally free sheaf of rank $< p$ placed in degree $0$. By definition

$c_ p(Z \to X, E) = c'_ p(\mathcal{Q}^\bullet )$

as bivariant operations (and not just on cycles over $X$) where the right hand side is the bivariant class constructed in Lemma 41.44.1 using $W, b, \mathcal{Q}^\bullet , T'$. By Lemma 41.44.4 we have

$P'_ p(\mathcal{Q}^\bullet ) \circ c = c \circ P'_ p(\mathcal{Q}^\bullet ) \quad \text{resp.}\quad c'_ p(\mathcal{Q}^\bullet ) \circ c = c \circ c'_ p(\mathcal{Q}^\bullet )$

in $A^*(Y \times _ X Z \to X)$ and we conclude. $\square$

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