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location Albany, CA
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visits member for 2 years, 10 months
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If I see further than most, it is because I have stood on the toes of giants and they kicked me high into the air...

However, there is nothing to suggest that I see further than most.

I am (inasmuch as one 'is' an occupation) an engineer. My mathematical skills are rather pedestrian, with a rare insight every now and then. I have been lucky enough to sit in the same room with some famous mathematicians & engineers. My Erdős number is 5, which undoubtedly makes me as unique as an Irishman in a pub. And I have been spotted in The Pub from time to time.

In professional circumstances, my value add has usually been the injection of common sense and completion of grunt work when perspectives and energies are unfocused.

My current age is the smallest number composed of the first two primes that would allow me to have watch on RTÉ the slightly contradictory small step for man and giant leap for mankind.

My real name is Joe Higgins. Apparently, my last name means 'of the Viking' in Irish.

My alma mater is University College, Cork in Ireland, and I had the additional privilege of obtaining my Phd. from the University of California at Berkeley under the enlightened tutelage of Lucien Polak.

I can be reached at joe dot higgins at gmail dot com.


Sep
5
revised Showing that $C^1[0,1]$ is a Banach space with the $||f||=||f||_\infty + ||f^\prime||_\infty$ norm.
added 54 characters in body
Sep
5
comment Showing that $C^1[0,1]$ is a Banach space with the $||f||=||f||_\infty + ||f^\prime||_\infty$ norm.
@VincentBoelens: You are right, I think my argument is circular.
Sep
5
comment Showing that $C^1[0,1]$ is a Banach space with the $||f||=||f||_\infty + ||f^\prime||_\infty$ norm.
@VincentBoelens: Since $D$ is continuous and $f_n \to f$ (in $\|\cdot\|$), we have $Df_n \to Df$.
Sep
5
answered Show A and B have a common eigenvalue
Sep
5
comment A circle is a set of measure zero. Generalizations?
+1: Very nice. ${}{}$
Sep
5
comment A circle is a set of measure zero. Generalizations?
My apologies, I was thinking of the range...
Sep
5
revised A circle is a set of measure zero. Generalizations?
added 549 characters in body
Sep
5
answered A circle is a set of measure zero. Generalizations?
Sep
5
answered Showing that $C^1[0,1]$ is a Banach space with the $||f||=||f||_\infty + ||f^\prime||_\infty$ norm.
Sep
5
comment Showing that $C^1[0,1]$ is a Banach space with the $||f||=||f||_\infty + ||f^\prime||_\infty$ norm.
Well, you start with a Cauchy $f_n$ and the standard route gives $f_n \to f$ and $f'_n \to g$ for some $f,g$. You need to show that $g = f'$.
Sep
5
comment Find the speed of an object given two vectors
I think it helps to draw the wind vector at the head of the airplane velocity. The 339.36 number comes from the horizontal component only. When you sum the square of this and the vertical component and then take the square root you get your final answer.
Sep
5
comment Heat Equation Two Conditions
You just need to deal with the discontinuity and any related convergence issues (presumably you are using Fourier series here?). Imagine the initial condition as two half-length rods being brought together.
Sep
5
comment Heat Equation Two Conditions
Is $f({L\over 2}) = g({L \over 2})$?
Sep
5
comment Proof check from basic set theory
This is good. The one to be careful with is $f( \cap_\alpha E_\alpha)$.
Sep
5
comment subset of critical points is closed
What is a critical point? If it means zero slope, then you can always pick some convergent sequence of critical points $c_n \to c$ and figure out what $f'(c)$ is.
Sep
5
comment Differential equation notation(syntax?) concern
The third step should be $- {1 \over r} \ln Q$.
Sep
4
answered Determinant question $\det(A^{-1/2}) = \det(A)^{-1/2}$
Sep
4
answered Showing an Absolute Value Inequality Problem Proof
Sep
4
answered Upper bound on $\sum_{n=1}^N \frac{1}{n}$
Sep
4
comment Help with prove of inf.
Why the downvote?