David Cary
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 Mar 17 awarded Revival Jan 22 suggested rejected edit on What is the capacity of a channel which doesn't allow subsequent 1's? Sep 3 awarded Yearling Aug 31 awarded Popular Question Jul 30 awarded Nice Answer Jul 14 awarded Nice Question Jul 8 revised In a finite field, is there ever a homomorphism from the additive group to the multiplicative group? clarify, I hope. Jul 8 comment In a finite field, is there ever a homomorphism from the additive group to the multiplicative group? @MorganRodgers: You are right that the additive group of integers modulo 4 has a completely different addition operator than GF(4), the finite field of four elements {0, 1, a, 1+a}. I don't know what I was thinking. You are probably right that I am "simply" mapping GF(5) to itself using additive notation in A and multiplicative notation in M -- but isn't that almost exactly what the original question asked for? Jul 8 revised In a finite field, is there ever a homomorphism from the additive group to the multiplicative group? fix oops pointed out in comments Jul 7 comment In a finite field, is there ever a homomorphism from the additive group to the multiplicative group? @MorganRodgers: In the first example, the finite field A is the additive group of integers modulo 4 -- or in other words, A is the set of four integers {0, 1, 2, 3}. In the second more general example, A is the additive group of of integers modulo N-1, where N is a Fermat prime. (The first example is a special case of the second example). How could I edit this answer to make that more clear? Jun 18 comment insphere/circumsphere ratio of a polyhedron the same as its dual polyhedron? You may want to look at David Moews answer, which already covers all those shapes. Do you have anything to add that isn't already covered by that answer? Jun 18 comment insphere/circumsphere ratio of a polyhedron the same as its dual polyhedron? The original question already pointed out that the ratios seemed to be equal for the duals of the 5 Platonic solids. This answer shows that the ratios actually are exactly equal, which is nice to know. What about other dual solids, such as the triangular prism and its dual the triangular bipyramid, the cuboctahedron and its dual the rhombic dodecahedron, the Archimedean solids and their duals the Catalan solids, etc.? May 19 awarded Revival Apr 25 awarded Civic Duty Apr 18 answered If $f(t)$ is periodic, is there any $t$ that would equal to DC components? Apr 5 awarded Popular Question Feb 18 answered In a finite field, is there ever a homomorphism from the additive group to the multiplicative group? Dec 20 awarded Caucus Oct 7 awarded Revival Sep 3 awarded Yearling