DOI: 10.1017/s1474748026101923 ISSN: 1474-7480

CHERN CLASSES FROM MORAVA K-THEORIES TO

Abstract

We study non-additive operations from algebraic Morava K-theories to oriented cohomology theories in algebraic geometry. For oriented cohomology theory

A $A$ upper A
that has a
p n $p^n$ p Superscript n
-typical formal group law over a
Z ( p ) $\mathbb {Z}_{(p)}$ double struck upper Z Subscript left parenthesis p right parenthesis
-algebra we construct ‘Chern classes’ from the algebraic
n $n$ n
-th Morava K-theory with
p $p$ p
-local coefficients to
A $A$ upper A
. If the coefficient ring of
A $A$ upper A
is a free
Z ( p ) $\mathbb {Z}_{(p)}$ double struck upper Z Subscript left parenthesis p right parenthesis
-module we also prove that these Chern classes freely generate all operations from
K ( n ) i n t ∗ $\mathrm {K}(n)_{int}^*$ normal upper K left parenthesis n right parenthesis Subscript i n t Superscript asterisk
to
A $A$ upper A
.

Examples of such theories are algebraic Morava K-theories

K ( n m ) i n t ∗ $\mathrm {K}(nm)_{int}^*$ normal upper K left parenthesis n m right parenthesis Subscript i n t Superscript asterisk
for all
m ∈ N $m\in \mathbb {N}$ m element of double struck upper N
and Chow groups with p-local coefficients. The universal
p n $p^n$ p Superscript n
-typical oriented theory is
B P { n } ∗ $BP\{n\}^*$ upper B upper P left brace n right brace Superscript asterisk
whose coefficient ring is also a free
Z ( p ) $\mathbb {Z}_{(p)}$ double struck upper Z Subscript left parenthesis p right parenthesis
-module.

Chern classes from the

n $n$ n
-th algebraic Morava K-theory
K ( n ) i n t ∗ $\mathrm {K}(n)_{int}^*$ normal upper K left parenthesis n right parenthesis Subscript i n t Superscript asterisk
to itself allow us to introduce the gamma filtration on
K ( n ) i n t ∗ $\mathrm {K}(n)_{int}^*$ normal upper K left parenthesis n right parenthesis Subscript i n t Superscript asterisk
. This is the best approximation to the topological filtration obtained by values of operations and it satisfies properties similar to that of the classical gamma filtration on
K 0 $\mathrm {K}_0$ normal upper K 0
. The major difference from the classical case is that Chern classes from the graded factors
g r γ i K ( n ) i n t ∗ $gr^i_\gamma \mathrm {K}(n)_{int}^*$ g r Subscript gamma Superscript i Baseline normal upper K left parenthesis n right parenthesis Subscript i n t Superscript asterisk
to Chow groups with p-local coefficients are surjective for
i ≤ p n $i\le p^n$ i less than or equals p Superscript n
, which allows to estimate
p $p$ p
-torsion in Chow groups of codimension up to
p n $p^n$ p Superscript n
of some varieties.