#mathober

[mathhombre]

Other Options

A bit of doodle doggerel for Mathober Day 7: Skew.

Trying to channel my inner Grant Snider.

[talkingnumbers]

Famous Sections

Have you noticed how mathematicians overuse vocabulary? It starts out logically, like cutting up solids with planes, but pretty soon it's all fiber bundles and manifolds.

Dorothy Bernstein was a great US mathematician, first woman president of the MAA, reputed to be a hell of a teacher, but I made up this factoid.

Mathober prompt 4: Section

[hombrepolitico]

There's an October drawing challenge for math called #mathober, and when this image came to me for the theme hole.

[thesoundofsanfranciscorpg]

[mainul1988-blog]

Search engine optimization (SEO) is the art and science of driving targeted website traffic to your website from search engines.

[majoyosei]

[#Gift] Victorian Couple

Another drawing to remember 🥺

They are Piero Fuyumoe and Faty Mathob, old OCs of one of my childhood best friends 💜💙

Today is her birthday and I wanted to draw them as a memory of the old days in which she came to my house to draw with me and we created stories together 🥰

I love you my precious nee and I hope you like this little present, Piero and Faty always will live in my heart, just like you, Happy Birthday!!! 🎉🎂🥳

Without more to say, I hope you like it!! 🍰

[embroiderygang]

Semana 1

¡Hazlo como niña!

Mathob

[mathhombre]

Weak Topology

A topological space is a set with a set of subsets, where the set of subsets is the topology. A topology is weaker or coarser than another topology if it is a subset. The weak topology is the weakest topology on a vector space so that the set of linear functions on the vector space is continuous.

This is a not accurate visualization, but it's what's in my head.

finer/stronger/bigger vs coarser/weaker/smaller

Mathober Day 6: Weak

My colleague Steven Schlicker has a fine, free undergraduate topology text. Great collections of problems. I'm so happy to be in a math department that emphasizes OER texts. Our math colleagues are miles ahead of us math ed folks with that.

[mathhombre]

MOVABLE

Mathober Day 22: Movable.

Originally I was going to do removable, but searching MathWorld for movable found this cool flexible polyhedron. Convex polyhedra have been shown to be rigid, but concave polyhedra can flex. Mathworld suggested this one.

Dashed lines are valley folds, interior solid lines are mountain folds, outside edges are whatever makes it work. Regardless, pretty fun tetradecahedron. I left tabs on alternating edges to help tape it together.

[talkingnumbers]

Supergraph

You'd think that Degree 4 vertex would be a dead giveaway.

A graph H contained in a graph G is a subgraph of G, but G is a supergraph of H. We just don't talk about it much.

Mathober Day 5: Supergraph.

[talkingnumbers]

But polyamorous might be more accurate.

Mathober theme 1: Kiss

Always a mess to make multiply tangent circles, because it's about hyperbolas intersecting. But each hyperbola has two branches and when you move them around the intersections switch among the four possibilities...

[talkingnumbers]

Postulater

Mathober Day 23: Axiom

Weak pun but I enjoyed it, and always think it.

[talkingnumbers]

Triangle Perspective

Mathober Day 19: Diagonal

Who you calling off kilter?

[talkingnumbers]

Calaveras de Matemáticas 2023

I like my last sketch for #mathober to be a memorial for Día de los Muertos. I'd say inspired by Posada, but that would be insulting him!

In the past year we lost Evelyn Boyd Granville, one of the pioneering Black women mathematicians of NASA. I thought Vicky Neale, lost too soon, would enjoy talking to her about women in math as she was a great advocate.

Louis Nirenberg and Joseph Kohn were collaborators in complex analysis.

Thomas Romberg, math teacher educator and organizer, is celebrating this great collection exemplifying one of his great maxims, that math is a human activity.

Looking down on them is the only one of these I got to meet, Eugenio Calabi. Great geometer and an amazing gentleman. He'd even talk to lowly grad students if they were talking about a good problem. I loved hearing him and Toby Colding discussing math way above my paygrade.

Grant eternal rest unto them, Oh Lord, and may perpetual light shine upon them.

[mathhombre]

Symmedian

Day 2 of Mathober is Symmedian.

Had to remind myself what that means, the reflection of the median across the angle bisectors (isogonal to the medians). And just like the medians are concurrent, then so are the symmedians, and their intersection is the isogonal conjugate to the centroid (the intersection of the medians).

There's an idea called the trilinear coordinates for a point in a triangle, and the trilinear coordinates for the symmedian intersection are the inverse of that for the centroid. I'm not sure how to produce the trilinear coordinates given a point, nor find a point from the trilinear coordinates. There's always more to learn.

This sketch generalizes the median to the corresponding points parameterized by t, and those segments isogonal segments. Pretty fascinating to me.

What do you notice and wonder?

Sketch is on GeoGebra.

[talkingnumbers]

Statistically Significant Drama

Mathober Day 18: Regression

This one might make sense!