Timeline for $\lambda$-ring structure defined for a graded ring in Fulton–Lang's book

4 events

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Sep 30, 2012 at 14:53	comment	added	darij grinberg		$1+t$ lies in $\Lambda^0_{\circ}\left(A\right)$, the $0$-th graded component of $\Lambda_{\circ}\left(A\right)$. Anyway, I guess James Borger understands better what Fulton and Lang were trying to say.
Sep 30, 2012 at 5:22	comment	added	Mahdi Majidi-Zolbanin		Dear Darij: Thank you for your suggestion. Are you sure $1+t$ (the $1$ of $\Lambda(A)$) is in $\bigoplus_{i\in\mathbb{N}}\Lambda^i_\circ(A)$? In any case, I think Fulton & Lang wanted a $\lambda$-ring structure on $\Lambda^\circ(A)$ to prove a Splitting Principle for abstract Chern classes (Theorem 3.1), which in the geometric case is evident. But even with your suggestion, I am not sure if it is possible to fix the proof of Theorem 3.1, because I believe the proof has other issues, e.g., I think they mix up the notion of $\lambda$-homomorphism introduced on page 15 with $\lambda$-ring homomo.
Sep 29, 2012 at 21:33	history	edited	darij grinberg	CC BY-SA 3.0	added 132 characters in body
Sep 29, 2012 at 17:03	history	answered	darij grinberg	CC BY-SA 3.0