Author Archives: Xander

About Xander

Xander completed his PhD in mathematics at UC Riverside in the Spring of 2020, amidst the COVID-19 pandemic. His thesis, titled Fractal Zeta Functions in Metric Measure Spaces, explores some connections between the geometry of certain metric spaces, and the spectra of the Laplace operator on those spaces. He is currently an instructor at Northland Pioneer College, out in the beautiful deserts of northern Arizona.

Local Fractal Zeta Functions

The 2020 Joint Mathematics Meetings were held in Denver last week. While at the Joint Meetings, I had the opportunity to present some of my more recent work in the AMS Special on Fractal Geometry, Dynamical Systems, and Applications. Slides … Continue reading

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Kites and Darts

My wife and I just bought a house. As part of the move, I decided to give our daughter’s room a more interesting paint job. We finally agreed on a Penrose tiling in purple and pink. It turned out rather … Continue reading

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Fractals 6 Slides

On Saturday, I will be presenting some of my recent work, which extends Michel Lapidus’s theory of complex dimensions in \(\mathbb{R}^n\) to a larger class of homogeneous metric measure spaces. In particular, I will be discussing the complex dimensions of … Continue reading

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UCR Beamer Template

For those that are interested, my UCR themed Beamer template is available here.

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Some Trig

A large portion of the “standard” precalculus curriculum consists of a rather tedious recitation of trigonometric identities. I am largely of the opinion that there are only a couple that one really needs to know—for example, the Pythagorean identity (\(\sin(\theta)^2 … Continue reading

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My wife brought home a loaf bread this weekend. The nutrition label reads as follows: I’m not entirely sure how one loaf of bread can consist of only 4.5 servings when a single serving is one ninth of a loaf. … Continue reading

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Seminar Talk in FRG

I gave a talk last week before the Fractal Research Group at UCR. The goal was to introduce my colleagues to the Assouad dimension, and to share some of the more interesting and/or surprising results. My notes (typos and all) … Continue reading

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The Sphere is Weakly Dense in the Ball

Another qual question, this one dealing with Hilbert spaces and the weak topology: Exercise: Let \(\mathcal{H}\) be an infinite dimensional Hilbert space. Show that the unit sphere \(S := \{x\in\mathcal{H} : \|x\| = 1\}\) is weakly dense in the unit … Continue reading

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Nowhere Differentiable Functions

In an undergraduate analysis class, one of the first results that is generally proved after the definition of differentiability is given is the fact that differentiable functions are continuous. We can justifiably ask if the converse holds—are there examples of … Continue reading

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An Elementary Duality Result

The following problem is a fairly straightforward exercise that seems to come up fairly often on qualifying exams at UCR, and I think that I finally have a nicely argued proof. I am going to put it up here mostly … Continue reading

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