On the computation of Kähler differentials and characterizations of Galois extensions with independent defect

Fuente: arXiv
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Autori principali: Cutkosky, Steven Dale, Kuhlmann, Franz-Viktor, Rzepka, Anna
Natura: Preprint
Pubblicazione: 2023
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author Cutkosky, Steven Dale
Kuhlmann, Franz-Viktor
Rzepka, Anna
author_facet Cutkosky, Steven Dale
Kuhlmann, Franz-Viktor
Rzepka, Anna
contents For important cases of algebraic extensions of valued fields, we develop presentations of the associated Kähler differentials of the extensions of their valuation rings. We compute their annihilators as well as the associated Dedekind differentials. We then apply the results to Galois defect extensions of prime degree. Defects can appear in finite extensions of valued fields of positive residue characteristic and are serious obstructions to several problems in positive characteristic. A classification of defects (dependent vs.\ independent) has been introduced by the second and the third author. It has been shown that perfectoid fields and deeply ramified fields only admit extensions with independent defect. We give several characterizations of independent defect, using ramification ideals, Kähler differentials and traces of the maximal ideals of valuation rings. All of our results are for arbitrary valuations; in particular, we have no restrictions on their rank or value groups.
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id arxiv_https___arxiv_org_abs_2305_10022
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the computation of Kähler differentials and characterizations of Galois extensions with independent defect
Cutkosky, Steven Dale
Kuhlmann, Franz-Viktor
Rzepka, Anna
Commutative Algebra
12J10, 12J25
For important cases of algebraic extensions of valued fields, we develop presentations of the associated Kähler differentials of the extensions of their valuation rings. We compute their annihilators as well as the associated Dedekind differentials. We then apply the results to Galois defect extensions of prime degree. Defects can appear in finite extensions of valued fields of positive residue characteristic and are serious obstructions to several problems in positive characteristic. A classification of defects (dependent vs.\ independent) has been introduced by the second and the third author. It has been shown that perfectoid fields and deeply ramified fields only admit extensions with independent defect. We give several characterizations of independent defect, using ramification ideals, Kähler differentials and traces of the maximal ideals of valuation rings. All of our results are for arbitrary valuations; in particular, we have no restrictions on their rank or value groups.
title On the computation of Kähler differentials and characterizations of Galois extensions with independent defect
topic Commutative Algebra
12J10, 12J25
url https://arxiv.org/abs/2305.10022