Will Jagy

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Name Will Jagy
Member for 3 years
Seen 4 hours ago
Website
Location Berkeley, California
Age 56
My main activity is in number theory of integral positive ternary quadratic forms. This began through years of working with Irving Kaplansky. Much of his unpublished writing on quadratic forms can be found as pdfs at http://zakuski.math.utsa.edu/~kap/forms.html and about Lie and Jordan superalgebras at http://zakuski.math.utsa.edu/~kap/superalgebra.html One of my own email addresses can be found easily using the search feature at http://www.ams.org/cml and just putting in my last name
May
15
 answered Did Smith correctly state the mass formula?
May
13
 comment Another colored balls puzzle (part II)
You really need to choose your friends more carefully.
May
12
 comment The Isoperimetric problem for domains constrained to lie between two parallel planes
Oh, including contact pieces with the planes. That explains the oval pictures.
May
12
 revised The Isoperimetric problem for domains constrained to lie between two parallel planes
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May
12
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May
12
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May
12
 answered The Isoperimetric problem for domains constrained to lie between two parallel planes
May
9
 comment Translation of Kähler’s “Über eine bemerkenswerte Hermitesche Metrik”
The unusual thing is that there was an early translation into Mongolian. You don't see that every day.
May
9
 comment Translation of Kähler’s “Über eine bemerkenswerte Hermitesche Metrik”
Did you do this yourself? If so, at least put a line in the document about translated by _ and perhaps a date, maybe the original title and full reference. My friend Dmitry does this sometimes from Russian, he did all that just for a three page thing that noone but I would ever see.
May
8
 comment Filling in a rational orthogonal matrix given one row
Thank you. I had that article at one point.
May
8
 comment (localized) L^2 norm of quasimode for Laplacian
crosspost math.stackexchange.com/questions/384999/…
May
6
 comment Filling in a rational orthogonal matrix given one row
@Gerhard, I used to have a very nice bathroom scale, based on strain gauge. Later I dripped a bunch of water on it and it died. en.wikipedia.org/wiki/Weighing_matrix Will Orrick is an MO regular, not sure about the other name. It appears the important case for most people has entries $0,1,-1.$
May
6
 revised Filling in a rational orthogonal matrix given one row
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May
6
 comment Filling in a rational orthogonal matrix given one row
@Tony, yes, I pay attention to that. If I click in the middle, where it currently says "edited 13 mins ago" it shows me the revision list and the official edit count. So that is how I know when to start an answer of my own, for example.
May
6
 comment Filling in a rational orthogonal matrix given one row
That's nice, if you do a large number of edits, but they are all in a few minutes, it clumps them together and counts only one edit.
May
6
 revised Filling in a rational orthogonal matrix given one row
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May
6
 asked Filling in a rational orthogonal matrix given one row
May
6
 comment Galois group of constructible numbers
In case it helps, adjoining $i$ to your field gives all constructible points in the plane, regarded as $\mathbb C.$ I found it useful.
May
6
 comment Is rigour just a ritual that most mathematicians wish to get rid of if they could?
fedja, there are courses en.wikipedia.org/wiki/Assertiveness#Training where you can learn to deal with your crippling inhibitions, then speak as you truly feel.
May
4
 comment When is the set of numbers represented by certain quaternary quadratic forms completely multiplicative?
@Yazdegerd, It would be nice if you could elaborate on that a little. I now know something of Cassels-Davenport owing to communication with Pete Clark. Meanwhile, a simple conjecture I settled on was $ f(x,y) + f(z,t) $ where $f$ is a positive binary form of order three in the class group. Maybe I can find it, Noam Elkies proved it for $f(x,y) = 3 x^2 + 2 x y + 4 y^2.$ It is true if $f$ is the principal form, roughly by quaternion multiplication.
Apr
27
 comment 3SAT to Quadratic Diophantine Equation?
mathoverflow.net/questions/36420/…
Apr
27
 comment Is rigour just a ritual that most mathematicians wish to get rid of if they could?
Comfort for the perplexed: $$\begin{array}{l}\text{Ring the bells that still can ring,}\cr \text{Forget your perfect offering,}\cr \text{There is a crack in everything,}\cr \text{That's how the light gets in.}\end{array}$$ Listen: youtube.com/watch?v=cgYlqKxV54Q
Apr
26
 comment Incidences of quadratic forms and points
What?${}{}{}{}$
Apr
25
 revised quick question about Drinfeld’s 2-page paper “Two Theorems on Modular Curves”
link to Russiam original
Apr
23
 revised Is there an approach to understanding solution counts to quadratic forms that doesn’t involve modular forms?
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Apr
23
 revised Is there an approach to understanding solution counts to quadratic forms that doesn’t involve modular forms?
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23
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23
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Apr
23
 answered Is there an approach to understanding solution counts to quadratic forms that doesn’t involve modular forms?
Apr
19
 answered Mean convex embedded sphere and convex sphere
Apr
18
 comment Union of Associated Primes.
How's the hamstring?
Apr
15
 comment Can you prove that Average(f(x)) is not equal to f(average(x)) for non-linear f in more than one variable
PleaseHelpMe, when you say "average," do you mean a few dozen sextuplets $(z,y,x,w,v,u)$ as inputs, with the corresponding few dozen outputs? How many numbers are in a single output?
Apr
15
 comment Can you prove that Average(f(x)) is not equal to f(average(x)) for non-linear f in more than one variable
@Douglas, does not seem to be posted at math.stackexchange.com/questions?sort=newest where it would get more basic responses. Looking at it, I am not sure how the word average is being used. Some example calculations, here or at MSE, would probably settle the question.
Apr
12
 comment Numbers integrally represented by a ternary cubic form
@joro, thank you
Apr
12
 comment Numbers integrally represented by a ternary cubic form
Oh, EDIT spelled backwards is TIDE thus indicating the end of an edited section...
Apr
11
 comment Numbers integrally represented by a ternary cubic form
Thank you, Noam.
Apr
11
 revised Numbers integrally represented by a ternary cubic form
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11
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Apr
11
 comment Numbers integrally represented by a ternary cubic form
@Noam, thanks. I've been checking, it appears the only primes to worry about are 2 and 11. I do think that the polynomial is not divisible by 8 unless all three variables are even ( a small finite check mod 8, not done yet). Perhaps something similar for 11, not sure yet.
Apr
11
 comment Numbers integrally represented by a ternary cubic form
@joro, I don't believe that will be a problem here, but I will do some checking. The main thing is that this behaves very much as the principal binary quadratic form of a discriminant, there is a rule for multiplication.
Apr
11
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11
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11
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11
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Apr
11
 asked Numbers integrally represented by a ternary cubic form
Apr
8
 comment Approximate number of primes below a given integer?
@Joël, of course you are right. I would, however, like to see some evidence that the person asking knows what all the words mean.
Apr
6
 comment What analytic tools can provide a lower bound for this Diophantine equation?
or just read the references at en.wikipedia.org/wiki/Brocard%27s_problem
Apr
6
 comment What analytic tools can provide a lower bound for this Diophantine equation?
see math.stackexchange.com/questions/350637/…
Apr
6
 comment 2d bin packing problem, with opportunity to optimize the size of the bin
crosspost math.stackexchange.com/questions/352575/…
Apr
4
 comment New Geometric Methods in Number Theory and Automorphic Forms
I think describing my work here would be immodest.