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Uchida's Homomorphism Conjecture


Uchida's homomorphism conjecture asserts that open homomorphisms between the Galois groups of solvably closed Galois extensions of number fields recover unique field embeddings in the opposite direction. Let E_i/F_i be possibly infinite Galois extensions, where F_i is a number field and E_i is solvably closed. For every continuous homomorphism with open image

 alpha:Gal(E_1/F_1)->Gal(E_2/F_2),

the assertion is that there is a unique embedding j:E_2↪E_1 with

 g degreesj=j degreesalpha(g)

for every g in Gal(E_1/F_1). Such an embedding sends F_2 into F_1.


See also

Absolute Galois Group, Galois Extension, Galois Group, Number Field, Solvably Closed Field

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References

Hoshi, Y. "A Note on Open Homomorphisms Between Global Solvably Closed Galois Groups." Kodai Math. J. 49, 63-79, 2026. https://doi.org/10.2996/kmj49104.Milne, J. S. Fields and Galois Theory. Version 5.10, Sept. 2022. https://www.jmilne.org/math/CourseNotes/FT.pdf.

Cite this as:

Weisstein, Eric W. "Uchida's Homomorphism Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/UchidasHomomorphismConjecture.html

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