[iirc]

slicing cubes with planes

sometimes it’s good to think about elementary problems. One reason is because thinking about elementary problems lets you appreciate abstraction better! Elementary school fact: you can slice a cube with a plane to produce a hexagon. In order to do so, you will need to intersect all 6 planes of the cube. (In fact, any plane which intersects all 6 sides of the cube should get a hexagon.)

For example, here’s one slice (from Wikimedia commons)

Why it works: A hexagon has 6 sides; these correspond to 6 lines. The intersection of two non-parallel planes is a line. Thus a plane which intersects all 6 sides (bounded planes) of a cube will make a hexagon.

[iirc]

If you know about tech stuff, then you probably know that running htop on your linux computer displays a list of currently active processes. 

Pressing F5 toggles between sorted and tree views.

What do the nested lines in the “tree” view represent? Oh, they just show the processes which were spawned, and what their parents are!

All of the processes in the screenshot are nested multiple times; the outermost nesting belongs to the init process.

Surprisingly, there is another process called kthread (for kernel threads, maybe?) which does not have init as its parent! It’s not visible on the screenshot, though.

[iirc]

[iirc]

update-o

Summer’s coming to an end. Here’s what I’ve done: Events! * I marched in Toronto Pride 2017 * Taste of the Danforth (very crowded) * Field Trip - I saw Broken Social Scene live! * Twelfth Night in High Park

Citysploring * Walked by the waterfront * Fresh on Bloor, Fresh on Spadina. * Took the 501 up from Front. * Soon Tofu place from first year. Personal Develop-ment * ‘fessed up on crushes (x2) * somehow managed to buy a place downtown * CUT MY HAIR (amazing) Laptop upgrade * Switched to Linux * CMAKE * Apparently I know how to Maple now. * Wrote some scripts * Learned just how little I know Wow, doors open * Got accepted to Hack the North * FIRST UNDERGRAD MATH CONFERENCE (Montreal, you rock) * First TA offer (first-year calc, here I come) * somehow managed to finish my Western NSERC * pls hire me alec Piano * Waltz in A minor, get * Most of the Undertale Medley, get! * One ace piano teacher, get (and unget). etc etc etc. London, you were great. Montreal, you were great. Toronto -- let’s go!

[humansofnewyork]

“Just trying to raise a girl in a sexist world.” (Rio de Janeiro, Brazil)

[iirc]

A bit of independent study.

[iirc]

oh boy

the story thusfar: 1990s china: mom meets dad -> dad gets liver cancer (no, he doesn’t drink) -> dad is ~23 years old -> mom is carrying dad’s baby -> everyone tells the mom she’s crazy for keeping the baby -> mom is a stubborn **** and keeps the baby anyways -> dad passes away, mom misses his last words -> mom finishes accounting degree, goes to and gets her masters -> mom moves from home country to Canada with the baby for a better life -> baby grows up, doesn’t understand mom -> mom and daughter fight (all the time) -> daughter goes to university for pre-med -> mom gets diagnosed with terminal cancer -> mom dies. daughter misses her last words.

[iirc]

disjoint set ADTs

White: What good is a disjoint set ADT, anyways?

Black: Oh no, you've been reading Cormen et al.'s Introduction to Algorithms again, haven't you?

White: So many ackermann functions... the alphas are starting to make my head twirl.

Black: You just use the disjoint set ADT to group things together.

White: But... don't I already have that? Can't I just... group things... by making groups?

/ White takes out some hay. She puts the hay in separate stacks. /

White: There... done. And in O(1) time relative to the size of the original haystack, to boot!

Black: Yeah, here's where the "computer" part of "computer science" comes in ...

/ A bulldozer comes and blasts the hay into oblivion. /

White: ...What was that?

Black: I dunno. Segfault. Read error, array index out of bounds, something like that.

White: aAugh

/ White quietly weeps at her decision to become a computer science major. /

White: Why does everything hate me

Black: There there, it's alright. Someday, you'll be able to pass the hatred on to the next generation of programmers!

[iirc]

okay, so I’ve been working towards understanding the adversarial search algorithms in Russell and Norvig’s Intro to AI, and for fun I drew this procedure for “living a life”. In Intro to AI adversarial search is used for two-player zero-sum games, which is kind of contrived. There the AI can easily run into things like “analysis paralysis,” by trying to analyze (impossibly) the results of all states, and contingency plans for those states, and so on...  I think “search” is only the beginning of the story when it comes to AI, and I’d like to see something a little more dynamic than what’s been shown. For example, I think we humans get a lot of milage by our ability to analyze a goal, and continually break it down into (in business-speak) actionable subgoals.

A good AI should also be able to constantly assess the environment,  and evaluate or assign subgoals accordingly. Then the big question is, “What is a suitable master-goal for an AI?” (And who gets to decide?)

[iirc]

today we learn that 

1. balls are not spheres. balls are not spheres. once you consider the boundary of a ball, you drop down a dimension 2. the 2-sphere lies in 3 dimensions, but is diffeomorphic to the real plane (plus a point) 3. the complex projective space lies in 4 dimensions, but is diffeomorphic to the complex plane (minus a point) (== real plane minus a point, up to diffeomorphism) 4. antipodal identification on RP^1 (x,y gets identified with -x,-y -> ratio is the same) is equivalent to CIRCULAR identification on CP^1 (one way to see this: all great circles intersecting the north pole on the unit sphere map to the same line).

In conclusion: the complex projective space is a two-dimensional object: it is not equivalent to the set of all complex vectors with unit norm; it is equivalent to the set of all complex vectors, period (well, minus a point.)

here’s a pretty video of the hopf fibration, yay.

[verily-i-say]

[iirc]

I’m such a dumbass

--After every assignment ever (sob sob)

[fromgreecetoanarchy]

[d-lightfulexcess]

This is the punkest thing I have ever seen in my whole life.

[vrumblr]

This is the cutest shit.

[revelation19]

Proverbs 22:6

[iirc]

why are the C string library functions so disgusting

[okar-i]

if you are a woman

I was assaulted when I was nineteen.

Wait… No, that’s not right.

I was molested with I was eighteen.

No.

I grew up with strange men.

Yes.

There were rumors that there was someone in the family had molested a child.

Yes.

I grew up thinking it was natural to abuse women.

Yes.

That sex was non-negotiable.

Yes.

That it was the woman’s fault.

Yes.

I grew up around toxic femininity.

Yes.

Women too hesitant to stand up for themselves.

Yes.

To themselves.

(Yes.)

I grew up watching a man who hung himself

(Yes)

Because his wife disowned him

(Yes)

Because his children were taken away.

Because he could not afford to pay for them

Or for his ex-wife’s lawsuit

Or for his drink

Yes. Yes to all of that.

I grew up thinking that it was the woman’s fault

because no woman ever told me it wasn’t.

[iirc]

Incidentally, I don't talk much about this, but I grew up in the kind of community that would have voted for Donald Trump. The blue-collar white men and women. They are not all bad people. It is a depressing place to live, to be in that community. It is not easy, and they are not taught any better. So I can understand why they believe in Trump's vision, and why the tumblr (and in general, progressive liberal) community is scary, foreign, and distasteful for them.

Although of course that doesn't mean Trump's inauguration is going to be anything except (beyond, beyond) awful.

[iirc]

[Richard] Stallman started the GNU project (a recursively defined acronym for 'GNU’s not UNIX') ...

Michael Kerrisk, The Linux Programming Interface

[iirc]

Ay, it's four days away from my mom's birthday, and I'm very sad today. "What the hell, man?" I'm angry, and not angry, at all the doctors who misdiagnosed my mother. I'm angry, and not angry, that I still don't know why it happened. And I'm angry that it's very quiet today. Why did both my parents die? And why am I here now, separated from them and their history? I'm lucky to have the life I lead now, but sometimes I am very, very sad.