14,203 reputation
1239
bio website math.ubc.ca/~israel
location Vancouver BC
age 63
visits member for 3 years, 4 months
seen 33 mins ago
Associate Professor Emeritus, University of British Columbia, and Optimization Algorithms Researcher, D-Wave Systems, Burnaby BC

30m
comment Number of Matrices with bounded determinant
What is this $n$?
12h
awarded  ca.analysis-and-odes
15h
comment Magic squares with specific properties
... and one for $k=428$: $$ \pmatrix{ 63 & 99 & 157 & 109 \cr 116 & 102 & 98 & 112 \cr 97 & 138 & 86 & 107 \cr 152 & 89 & 87 & 100 \cr }$$
19h
answered Maximize combinatorial sum for boolean function
20h
comment Maximize combinatorial sum for boolean function
$n$ and $t$ given, $t > 1$? $(n-1)/t$ an integer? How did this problem arise?
22h
comment Lack of parabolicity of PDE due to invariancy under diffeomorphisms?
Ah, so you're talking about invariance under all diffeomorphisms...
22h
answered Lack of parabolicity of PDE due to invariancy under diffeomorphisms?
23h
revised Estimate maximal coefficient of a polynomial from a circle containing all roots
added 174 characters in body
23h
answered Estimate maximal coefficient of a polynomial from a circle containing all roots
1d
comment Ergodic theory reference for converging sequences of matrices
What if $A_1 = 0$?
1d
comment Magic squares with specific properties
@GerhardPaseman It doesn't work. I get 12 subsets besides rows and columns that sum to 430 - 43*4 = 258, e.g. entries (2,2), (2,3), (2,4), (3,2),(3,4): $47+51+50+46+64=258$.
1d
answered Magic squares with specific properties
1d
comment Magic squares with specific properties
$k=430$ (must be getting close to optimality...): $$ \pmatrix{ 62 & 152 & 104 & 112 \cr 153 & 90 & 94 & 93 \cr 102 & 89 & 132 & 107 \cr 113 & 99 & 100 & 118 \cr }$$
1d
revised Identity involving shifted Legendre coefficients
added 58 characters in body
1d
answered Identity involving shifted Legendre coefficients
1d
answered Uniqueness of solution of a nonconvex optimization problem
1d
comment Identity involving shifted Legendre coefficients
You don't want that $(-1)^n$: it should be just $-1/(4n^2-1)$.
2d
awarded  nt.number-theory
2d
answered Asymptotics and error terms for an arithmetic function built upon $\omega$ and $\Omega$ functions
2d
comment Magic squares with specific properties
$k = 435$ using tabu search: $$ \pmatrix{ 109 & 104 & 148 & 74 \cr 85 & 106 & 82 & 162 \cr 123 & 115 & 111 & 86 \cr 118 & 110 & 94 & 113 \cr}$$