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bio website math.ubc.ca/~israel
location Richmond, Canada
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visits member for 2 years, 2 months
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I'm an Emeritus Associate Professor of Mathematics at University of British Columbia and an Optimization Algorithms Researcher at D-Wave Systems in Burnaby BC


May
6
answered To solve a differential equation
May
6
answered roots of the polynomial equations and relation among the coefficients
May
6
comment Dividing and multiplying surds - Rule
It's not true if $x$ and $y$ are negative.
May
5
comment Every exposed point is a extreme point
Your definition of exposed point is not quite right. You want $H$ to be a supporting hyperplane, not just any hyperplane.
May
5
revised Showing that the inverse of the perturbation of a compact operator by a bounded operator remains compact.
added 87 characters in body
May
5
answered linear functional-equation $ \,2f\left(x+1\right)=f\left(x\right)+f\left(2x\right) $
May
5
comment linear functional-equation $ \,2f\left(x+1\right)=f\left(x\right)+f\left(2x\right) $
But "all functions $R \to R$" says that it doesn't have to be continuous.
May
5
comment Showing that the inverse of the perturbation of a compact operator by a bounded operator remains compact.
In this setting, $L^{-1}$ bounded does not imply $L$ bounded: $L$ is not defined on all of $H$ but only on a subspace.
May
5
revised Showing that the inverse of the perturbation of a compact operator by a bounded operator remains compact.
added 92 characters in body
May
5
answered Showing that the inverse of the perturbation of a compact operator by a bounded operator remains compact.
May
5
answered What is the image of the strip $0\le\Re(z)\le2$ under $z\mapsto\dfrac{1}{z}?$
May
5
comment Notation for number of value changes in a sequence
$\delta_{ij}$ is the Kronecker delta, which is $1$ if $i=j$ and $0$ otherwise.
May
4
awarded  Enlightened
May
4
awarded  Nice Answer
May
4
awarded  statistics
May
3
answered Notation for number of value changes in a sequence
May
3
comment If $f$ is entire and $g$ has an essential singularity, must $f\circ g$ have an essential singularity?
... namely the Casorati-Weierstrass theorem. Also you need that $f$ has dense range, which is a corollary of Liouville's theorem.
May
3
revised I roll 6-sided dice until the sum exceeds 50. What is the expected value of the final roll?
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May
3
answered I roll 6-sided dice until the sum exceeds 50. What is the expected value of the final roll?
May
3
comment Find all functions $f$ that assign a real number $f(x)$ to every real number $x$ . . .
No, $f(x) = a x + b$ is always a solution.