Hacker News new | past | comments | ask | show | jobs | submit login
Math Exposition on YouTube (dustingmixon.wordpress.com)
140 points by mathfan on Aug 5, 2023 | hide | past | favorite | 33 comments



As a maths graduate from nearly 40 years ago I've forgotten far more than I remember, but really enjoy little 10-15 minute snippets of calculus and analysis on YouTube that tickle the rusty old neurons. Current favourite is Michael "and that's a good place to stop" Penn.


I'm the same as you )other than being a Physics graduate). Love Michael Penn. Interesting topics with a good but not pedantic level of rigor.

https://youtube.com/@MichaelPennMath


I'm a huge fan of Michael Penn's intro to various subfields of math videos, like the one on vertex algebras. He does a great job of balancing definition with motivation so that it doesn't feel like wading through a meaningless sea of symbols.


Forgetting so much is my current fear as well. What did you end up doing?


It hasn’t been nearly so long for me, but I’ve managed to hold on to much of the math I’ve learned by re-proving theorems I’d learned and solving problems in my head during downtime, while doing household chores, and while falling asleep. Another benefit is that I am almost never bored since there’s always more math to do.


Just block off regular times to do the math you want to remember a few times per week at least. Maybe even 30+ minutes per day.

Solve problems. Prove things. Etc.


The video had me until the punchy end.

The visual walkthrough of their proof was elegant in its exposition.

I understand the humor makes it more fun to work on and self effacing, but you hooked me with this novel tool to analyze political districts, and rather than process all of them and report on the findings, it was merely used to “own the libs”?

Are all the claims of gerrymandering false based on this metric?

What happens when you change the 40% for the minority metric?

I guess I discovered I would rather dwell on the abstraction of “arbitrarily extreme constants”.


This is a great explanation of why districts themselves are bad. We need proportional representation with either no districts at all or large multi-member districts.


I'm not sure districts are inherently bad. The concept that people living in the same geographic area will have similar concerns that need to be addressed makes sense to me.

I think my preference would be districts defined by geographic features and boundaries paired with a different set of elected officials determined by the type of proportional representation without any limits on geographic boundaries.


> he concept that people living in the same geographic area will have similar concerns that need to be addressed makes sense to me.

This is true but then there are other buckets as well. Why should location be the only organizing principle, when we know there are a bunch of concerns that aren't tied to it?

Why not have virtual districts across dimensions? You get a vote for your birth year cohort, a vote for your geographical district, and a vote for your income bracket group. Parliament will be this weird 3D set of people chosen to represent various interests.

Or we just do proportional representation. I find it hard to justify FPTP, it causes wild distortions.


Just think of the gerrymandering opportunities such a system would present...


As long as there's a separate vote for each dimension, this seems like an improvement. Gerrymandering would be significantly harder on age and income, since they're one-dimensional. If age is defined by birth year, then that would have no gerrymandering at all.


You don't need proportional representation to get away from FPTP. Approval voting and score voting look especially good and they wouldn't require a change to the constitution.


> You don't need proportional representation to get away from FPTP.

But you should, since proprortionality as a property has strong evidence of being practically producing better piblic satisfaction with government, as well as having a strong theoretical argument for being the best measure of the degree to which a “representative” body actually is representative.

> Approval voting and score voting look especially good and they wouldn't require a change to the constitution.

Approval voting and score voting look especially bad for public elections in a multicultural society, since they call for abstract ratings that where there are well-established cultural variations in assignment for the same actual sentiment, and treat them as having consistent meaning.

And rough PR in the House (e.g., by STV) doesn't require a Constitutional amendment, either, only a statutory change.


there's no evidence that proportional repreesntation can achieve a higher level of voter satisfaction than good single-winner methods like score voting or approval voting.

and besides, you won't get PR at any scale beyond a handful of cities without first escaping duopoly, which requires score voting or approval voting as a prerequisite.

http://scorevoting.net/PropRep


> there's no evidence that proportional repreesntation can achieve a higher level of voter satisfaction than good single-winner methods like score voting or approval voting

Proportional representation isn’t a method, its an axis of measurement, and there is very good evidence that better performance on that axis produces better outcomes in terms of satisfaction with government among the citizenry.

There is neither evidence nor even a theoretical reason to think that what you call “good” single winner methods (which are “good” only by abstract mathematical criteria only applicable to single-winner methods which themselves have no empirical link to good outcomes, and which make assumptions like that ballot markets have some consistent meaning across voters that are known false for the kind of rating systems they use) either would in practice perform good (or even better than FPTP) on that measure or defy the observed relation of that measure with satisfaction.

> and besides, you won't get PR at any scale beyond a handful of cities without first escaping duopoly, which requires score voting or approval voting as a prerequisite

This first part of that sentence is a ludicrous claim offered with no support. If you mean “you can't establish a better voting method without buy-in from those elected under the current methods”, that’s false in any jurisdiction with citizen initiatives (as many US states have). Whether states adopting this can be sufficient to create political pressure to negate the problem on a national basis is... well, that's certainly a question.

If you mean “no matter what voting method you adopt, it won’t produce very proportional results as long as there is an existing duopoly for incumbent officeholders in the same body”, perhaps because of some kind of partisan/media momentum effect, then there is probably a kernel of truth there, in that it will probably take more than one electoral cycle to transition to producing results close to the natural degree of proportionality of the new voting method if it is radically divergent from the former one, but that's a frictional effect, not a binary switch.

The second part, though, is even worse. There is neither evidence nor even a good theoretical argument to suggest that there is some scale where you can’t get from FPTP to something producing more proportional results without the first step being score or approval voting. And your link provides neither evidence or argument on this point, only the bare claim that the author(s) “very much doubt you are going to get it” without range (i.e., Score) voting (apparently rejecting your claim that Approval is viable) as a “preparatory step”.


You should look into the German system.

How it is supposed to work is that 50% of representatives are 'local' representing a region (of roughly 300.000 people) and the remaining 50% of representatives ensure proportionality.

So, imagine the CDU (centre-right party) wins 40% of the voting share, but 60% of the seats, the SPD (centre-left) 30% of both voting share, and seats, the Greens 20% of the share but only 10% of the seats, and the FDP 10% of the share and no seats. The seats to ensure proportionality would be distributed 20%, 30%, 30%, 20% respectively.

There are a lot of subtleties to the system to ensure true proportionality that I won't go into right now, and tend to lead to the parliament growing (if things work perfectly there should be 598 seats, but currently there are 736), but broadly the system works.


It leads straight to influencing a conveniently small group of people with other means. If you follow US politics even remotely, the term "pork (barrel)" should be enough to convince you that local representation is a bad idea. Clientelism is also easier in smaller electoral areas. Now add both.

In proportional representation it is still possible to vote for a local candidate, depending on how it is organized. Voting for a party is the common thing, but allowing people to vote explicitly for a candidate lower on the list allows getting a local candidate straight into parliament. Not that that is ideal, but it is definitely not impossible.


I mean most European countries have some form of districs as well, it is just not a winner takes all approach.

Nobody cares how districts are shaped when there is no advantage in having them shaped a certain way.

I think the US system is undemocratic as it fails on some very fundamental levels to assure representation that honors the voter's will.


If the shape of the districts were truly irrelevant, what would the advantage of having them be, relative to a single district with proportional representation?


> I'm not sure districts are inherently bad. The concept that people living in the same geographic area will have similar concerns that need to be addressed makes sense to me.

Yes, it would make much more sense to define the districts by any of various obvious methods and then not worry about whether they have equal population.


but the point as i understand it is that then in most districts the minorities will never get a chance to elect representatives that favor them because they get outvoted by the majority.

but it bothers me that the solution to this problem is to redraw voting districts. and for a while i could not figure out why or what to do about it, but then i wondered, why not simply have multiple representatives for each district. say a dozen or so. that way there is enough room for each minority to be proportionally represented by candidates of their choice.

to make it more interesting, give each voter more than one vote, up to the number of representatives. then you add up all the votes and pick the top 12.

make the districts larger or add a second layer of voting to keep the total numbers of elected representatives down. with a second layer all elected would again elect a smaller number amongst themselves again allowing minorities to be represented.


More important: Direct Representation with optional Proxy (aka Representatives)

There's no reason the 60% should have thier will ignored just because thier votes are split between two or three parties and the remaining major party ekes out an extra 5-10% of the population than the next highest voted candidate (see canada for exactly this happening).

Each person should also be able to have thier will about a bill included in the voting at any time instead of having to hope whoever you voted to rep you actually does what they said let alone what you want.

That's way more important than the issue of districts (though that is an issue needing addressing its just not remotely as impactful in both the short and long term).


Proportional representation has problems too. There is no perfect system.


> There is no perfect system.

So what? FPTP is objectively the worst voting method, across pretty much all metrics (others may do slightly worse at local representation).

Also, proportional representation is a class of voting methods (my personal preference being STV).


Direct democracy it is then.



Meta:

Maybe this submission can use a more specific title? Referencing the topic -- the math behind ugly voting districts / gerrymandering.


Funny thing is, I would've thought "Why You Want Voting Districts To Be Ugly" is the better title, but I guess they're the experts. Something about the "4% pretty" statistic is unfamiliar enough to me to not make me want to click on the video. Maybe this is a super niche concern, though - I can easily imagine their version getting more clicks precisely because it's more novel.


these summer of math expositions are awesome, i love seeing these videos pop up en masse once a year.

i've got nothing to do with anything related to math but i really want to find a niche topic to delve into detail just to join in the sharing.


I always thought some aspects of how mathematics is taught has been wrong for a very long time. Part of it, I think, are people working as teachers/professors who are really bad teachers.

As an example: One that stuck in my head from decades ago was solving the Fibonacci recurrent relation. At some point the professor wrote down “r^n” and somehow “r^2 + r + 1 = 0” shows up.

When asked where r^n came from he said it was just a guess. When asked how or why not guess something completely different, he said “that’s how we solve these problems”.

And that was that. Nobody in his class understood this and myriad other areas in math where the answer seems to be “and then a miracle occurs”.

There are many YouTube math teacher who are massively better than most university (and below) instructors. My guess is this is because they actually love what they do.


I am mildly color blind, and all the orange and green voters in the grid look pretty much the same to me.


Mathologer is my favorite




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: