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Mar 19, 2011 at 12:17 history edited Chandan Singh Dalawat CC BY-SA 2.5
cosmetics; added 21 characters in body
Mar 19, 2011 at 10:36 history edited Chandan Singh Dalawat CC BY-SA 2.5
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Mar 19, 2011 at 6:40 answer added Chandan Singh Dalawat timeline score: 4
Jun 12, 2010 at 5:57 comment added Chandan Singh Dalawat Pour qu'une équation de degré premier soit résoluble par radicaux, il faut et il suffit que deux quelconques de ces racines étant connues, les autres s'en déduisent rationnellement (Évariste Galois, Bulletin de M. Férussac, XIII (avril 1830), p. 271).
May 13, 2010 at 14:38 comment added Emerton I should add: Kronecker did publish a proof of that result; I just don't understand why it wasn't already seen at the time to be a consequence of Galois's more general result.
May 13, 2010 at 14:36 comment added Emerton Yes, that is a very nice corollary. For a reason I don't understand (because of the chronology: Galois is well before Kronecker), that result is traditionally attributed to Kronecker. A highly recommened reference for the history of these ideas is Hans Wussing's "The genesis of the abstract group concept".
May 13, 2010 at 9:22 comment added Chandan Singh Dalawat Amazing! Great scholarship! I had guessed that such a result should be true from a reference to Artin's Galois Theory (Notre Dame notes), Chapter 3, Theorem 7, written by AN Milgram. He gives another nice corollary: a solvable irreducible prime-degree polymonial over a subfield of the reals has either (precisely) one real root or all its roots are real.
May 13, 2010 at 5:42 comment added Emerton A remark: this result is due to Galois himself, I believe. As an application: note that any subgroup of $AGL(1,p)$ that fixes two elements is trivial, and conversely, any transitive subgroup of $S_p$ with this property is contained in $AGL(1,p)$. Thus we get Galois's theorem: a prime degree irred. polynomial is solvable if and only if its splitting field is generated by any two roots. (This result was regarded as Galois's major contribution to the theory of equations for a decade or two after his death.)
May 13, 2010 at 1:57 history edited Chandan Singh Dalawat CC BY-SA 2.5
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May 11, 2010 at 4:34 vote accept Chandan Singh Dalawat
May 10, 2010 at 12:33 answer added Robin Chapman timeline score: 13
May 10, 2010 at 12:04 answer added Jack Schmidt timeline score: 12
May 10, 2010 at 11:26 history asked Chandan Singh Dalawat CC BY-SA 2.5