bio | website | zakuski.math.utsa.edu/~jagy |
---|---|---|
location | Berkeley, California | |
age | 58 | |
visits | member for | 4 years, 9 months |
seen | 22 mins ago | |
stats | profile views | 14,290 |
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 Much of his unpublished writing on quadratic forms can be found as pdfs at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
Oct 16 |
awarded | Good Answer |
Oct 16 |
comment |
Isotropy of Apollonian disk-packing
@JosephO'Rourke, surprised that changing a single multiplier to $$ w^2 + x^2 + y^2 + z^2 = wx+wy+wz+xy+xz+yz $$ gives non-negative solution entries, a single root $(0,1,1,1),$ and a loss of the tree property, although still a partially ordered set... math.stackexchange.com/questions/966156/… |
Oct 16 |
comment |
Isotropy of Apollonian disk-packing
@JosephO'Rourke, twwo articles last year in the Bulletin, ams.org/journals/bull/2013-50-02/home.html one by Kontorovich, one by Fuchs. |
Oct 6 |
awarded | Nice Answer |
Oct 6 |
comment |
Longest sequence of sum of distinct squares
@RichardStanley, probably because the wording closely resembles the homework questions on MSE; something assigned rather than happened upon. |
Oct 5 |
revised |
Why do roots of polynomials tend to have absolute value close to 1?
added 43 characters in body |
Oct 5 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
@Lucia, thanks, i will edit that in. |
Oct 5 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
@AndrejBauer, glad you saw this. |
Oct 5 |
revised |
Why do roots of polynomials tend to have absolute value close to 1?
added 111 characters in body |
Oct 5 |
answered | Why do roots of polynomials tend to have absolute value close to 1? |
Oct 4 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
Igor, Eric Kostlan said the late post by Phantom Hoover is what he would have said, later added "Its even easier, if you are willing to be non-rigorous. If you generate random polynomials in any of a number of "natural ways", the middle coefficients tend to grow fast. For example, one model which gives roots equi-distributed on the Riemann sphere gives the i-th coefficient a variance of (n choose i). So forcing all the coefficients to have the same variance is sort of like forcing the middle coefficients to be zero. So roughly speaking, this starts to look like x^n +- 1." |
Oct 2 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
Igor, glad you think so. If he does not put anything on MO within a few days, I will forward your opinion. |
Oct 2 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
I see Eric's paper with Edelman is a reference for the Transactions article. I wrote to Eric, maybe he will have something to add. |
Oct 2 |
comment |
Why do roots of polynomials tend to have absolute value close to 1?
Just a name, my classmate Eric Kostlan worked on roots of random polynomials. See if I can find anything specific.. |
Sep 30 |
awarded | Explainer |
Sep 23 |
comment |
Bounds re Asymptotic Formula for the Sum of Largest Prime Factors
I don't see effective estimates; those are rare. The first edition of Handbook of Number Theory by Mitrinovich, Sandor, and Crstici point to a 1993 paper by J. Lin with a more precise estimate than yours, but still has an error term with unspecified constant. You might check the second edition. |
Sep 22 |
revised |
Constructing sums of squares identities
added 185 characters in body |
Sep 22 |
answered | Constructing sums of squares identities |
Sep 22 |
comment |
What do you call a fixed point theorem for a mapping from a subset of a space to the whole space?
@WłodzimierzHolsztyński, I do not actually know what theorems he has in mind; I am just picturing an open disc in $\mathbb R^2,$ continuous mapping, if you can just translate the thing you do not get any fixpoint; surjectivity would rule that out. Meanwhile, surjectivity is not a feature of Brouwer, Lefschetz theorems, where a space is mapped to itself. Oh, I think it disables @ signs when a notification will be automatic. |
Sep 22 |
comment |
What do you call a fixed point theorem for a mapping from a subset of a space to the whole space?
@WłodzimierzHolsztyński, alright. That strikes me as a possible name or part of a phrase, a likely feature of many such things, either as a hypothesis or early conclusion on the way to proof. |