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Let p be a rational prime, G a group of order p, and K a number field containing a primitive pth root of unity. We show that every tamely ramified Galois extension of K with Galois group isomorphic to G has a normal integral basis if and only if for every Galois extension L/K with Galois group isomorphic to G, the ring of integers in L is free as a module over the associated order . We also give examples, some of which show that this result can still hold without the assumption that K contains a primitive pth root of unity.
James E. Carter. "Some remarks on Hilbert-Speiser and Leopoldt fields of given type." Colloquium Mathematicae 108.2 (2007): 217-223. <http://eudml.org/doc/286266>.
@article{JamesE2007, abstract = {Let p be a rational prime, G a group of order p, and K a number field containing a primitive pth root of unity. We show that every tamely ramified Galois extension of K with Galois group isomorphic to G has a normal integral basis if and only if for every Galois extension L/K with Galois group isomorphic to G, the ring of integers $O_\{L\}$ in L is free as a module over the associated order $_\{L/K\}$. We also give examples, some of which show that this result can still hold without the assumption that K contains a primitive pth root of unity.}, author = {James E. Carter}, journal = {Colloquium Mathematicae}, keywords = {normal integral bases; class groups; associated orders}, language = {eng}, number = {2}, pages = {217-223}, title = {Some remarks on Hilbert-Speiser and Leopoldt fields of given type}, url = {http://eudml.org/doc/286266}, volume = {108}, year = {2007}, }
TY - JOUR AU - James E. Carter TI - Some remarks on Hilbert-Speiser and Leopoldt fields of given type JO - Colloquium Mathematicae PY - 2007 VL - 108 IS - 2 SP - 217 EP - 223 AB - Let p be a rational prime, G a group of order p, and K a number field containing a primitive pth root of unity. We show that every tamely ramified Galois extension of K with Galois group isomorphic to G has a normal integral basis if and only if for every Galois extension L/K with Galois group isomorphic to G, the ring of integers $O_{L}$ in L is free as a module over the associated order $_{L/K}$. We also give examples, some of which show that this result can still hold without the assumption that K contains a primitive pth root of unity. LA - eng KW - normal integral bases; class groups; associated orders UR - http://eudml.org/doc/286266 ER -