Abstract
The aim of the present paper is to explicitly construct canonical representatives in every strict isomorphism class of commutative formal groups over an arbitrary torsion-free ring. The case of an Z(p) -algebra is treated separately. We prove that, under natural conditions on a subring, the canonical representatives of formal groups over the subring agree with the representatives for the ring. Necessary and sufficient conditions for a mapping induced on strict isomorphism classes of formal groups by a homomorphism of torsion-free rings to be injective and surjective are established.
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References
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Bondarko, M.V. Canonical representatives in strict isomorphism classes of formal groups. Math Notes 82, 159–164 (2007). https://doi.org/10.1134/S0001434607070206
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DOI: https://doi.org/10.1134/S0001434607070206