circulating denominations (part 4)

… and wallet distributions.

This is part of the Toronto visit series.

“Do you have change for $5?”
“I can only give you one loonie and two lizes”
Dumps coins on counter.

(Canada has no bills under $5 and circulates the $1 and $2 coins.)

Before playing with Canadian money, I had thought that a $2 denomination, whether coin or bill, would be a great idea. But the problem I encountered here was that I was just unable to get very many $1 coins when the $2 coin was also widely circulating. This makes sense, because each transaction at most ends up giving you one additional $1 coin if done optimally. But if you had to always pay odd dollar-amount fees like the $3 streetcar fares, then you need many $1 coins which you don’t have. Compare this to the US system, where you get lots of $1 bills from daily transactions — up to four $1 bills in a transaction ($0-$4 in change). It surprised me that the latter situation is more flexible, because I did not take into account the dynamic effects that repeated transactions have.
(Read the article)

nchoosetwo and collaborative ranking

Walking around campus these days, there are cryptic-looking things like

\(\binom{n}{2}\mathrm{.com}\) and \(\binom{n}{2} \ni \binom{i}{u}\)

obviously referring to a dating site — currently it’s restricted to MIT and Harvard students. This one tries on an idea that I’ve heard discussed numerous times in different contexts, but apparently nobody went and did it in all these years. Instead of running a matching algorithm, it asks third parties (i.e. matchmakers) as well as the interested parties themselves to suggest matches. The thing that is supposed to keep this low-risk is anonymity: a match isn’t revealed until the two primary parties involved mutually accept or their lists intersect.

As with all things that involve anonymity, this asks for trollish and antisocial behavior. I’ve already registered three aliases on moira for exactly this purpose — ok, ok, so they’ve suppressed that antic after people raised concerns, though these and other ramifications should have perhaps been worked through a bit more carefully pre-launch.

The spam potential remains. A matchmaker’s identity isn’t revealed unless both people accept her suggestion, so pranks and insults can be conducted to an extent. One way around this may be grafting social graph data onto the system for collaborative filtering (if they manage to obtain such data…). And if they do, perhaps the suggestions of more closely related people should weigh more, along with those of successful matchmakers. Perhaps there should even be more weight if multiple matchmakers concur. This is extremely intriguing, because eliminating spam is equivalent to predicting who is a likely match, and collaborative filtering for this problem is an unexplored direction.

The more fundamental question is why such a site is even necessary.
(Read the article)


After some recent bouts of navel-gazing, it occurred to me that I had no idea what was on the other side of the navel. The umbilical cord couldn’t have been spilling nutrients into the abdominal cavity — so there must be something connected on the other side!

Turns out there is.
(Read the article)

climate engineering

Came across this the other day.

Climate engineering may happen but it seems like the energies available to control the weather/climate is not nearly enough (not even the same magnitude) to make this a stable plant. Frankly it seems like a bad idea at this stage of technological development. On the other hand, it is a valid point to say that the climate is already being engineered anyway (more and more) just by the very fact that we take input and commit output to the system. It doesn’t much matter that we still don’t know what we’ve been doing.

In this sense, I think the entire argument about whether global warming is happening or not or is the model believable or not or is it actually global cooling is beside the point. The actual effect doesn’t matter as much as the fact that we’re engineering any system beyond our capability to understand it, much less to control it. One day there may be a way to engineer the climate in a controllable, stable fashion. Before that, it is prudent to be paranoid about the inputs driving the system unless there is proof that said inputs do not drive one of the unstable modes of the system.

Fighting words and their consequences

Somebody is in the news recently for allegedly getting assaulted after uttering fighting words. It turns out fighting words are commonly excepted from protected free speech. Contrary to the elementary folklore, free speech appears not to be universal, but is thought to be based on the libertarian principles argued by Mill, that speech which does not do harm to others should not be proscribed. All right, so far this is all common knowledge. But is that all? Is free speech (harm or not) a flawed idea to begin with? There is an old and generally discursive article by Kendall called The “Open Society” and Its Fallacies, which challenges the tenets of Mill’s libertarian stance on speech at its core.
(Read the article)

sleep … and a smart alarm honor of the stupidity that is Daylight Savings Time, I’ll write about sleep.

First, this watch seems pretty interesting. It is based on the idea that if you’re never going to get enough hours of sleep a night anyway, then you are best to get a full number of sleep cycles, rather than a fractional one. So it tracks your sleep cycle and wakes you up when you’re most awake.

This reminds me of my general annoyance with the whole concept of sleep and the inefficiency it causes. Sleep has got to be one of the worst vestigial devices still left in humans, although not as bad as the appendix.

Years ago, I came across a blog in which the person was trying out the concept of polyphasic sleep, which is basically napping frequently for short periods each time. The idea was to save total amount of time slept, I guess, or to make sleep more efficient. I guess it worked out well enough to cause a whole bunch of fanatical people to try it.
(Read the article)

Toward a multi-input interface

I was recently shown this collaborative editor called Gobby (there are others) and was reminded of an idea I’ve been toying with for a long time.

A lot of work these days goes into novel human-computer interfaces (think coffee table displays, networked whiteboards, etc.) and gestures (think various touch responses like multi-touch zooming), but in my opinion (and metaphor), these work are like lightly scratching the skin when there is a deep deep itch.
(Read the article)

V I Fabrikant

Note: There has been some confusion about this post. Let me make it very clear — I am NOT Fabrikant, nor do I have any relation to him, or even know of him in any way. I just came across this hilarious correspondence address on the internet. I have NO idea who this guy is, or whether the people commenting below are who they claim to be.

Look at the correspondence address of this Journal of Applied Math article

Utilization of divergent integrals and a new symbolism in contact and crack analysis
VI Fabrikant

Prisoner #167932D, Archambault Jail, Ste-Anne-des-Plaines, Quebec, Canada J0N 1H0

Correspondence: Email: [email protected]

Received for publication 15 June 2006. Revision received 1 December 2006.

The main potential function, used for the complete solution of the contact and crack problems for elliptical domains, is presentable as an integral of an expression comprising a logarithm of a distance between two points. These integrals were considered to be impossible to compute, though various derivatives of these integrals were computed in the past. The new symbolism, introduced here, combined with utilization of divergent integrals, allows us to compute these integrals exactly and in a closed form. It also introduces a dramatic simplification in the final expressions and restores some mathematical symmetry and elegance.

You can look up this guy on Wikipedia.

daylight savings time

… is a stupid idea. Yes, daylight is nice to have, but then go to work from 7 to 4 instead of 8 to 5. The only reason to change the clocks instead of changing schedules is because changing schedules (and habits in general) is hard. So we must pretend 7AM is 8AM. In fact, as long as artificial lighting exists, having a non-symmetric waking schedule will always be the norm, I argue. If daylight savings time existed year-round, people would start going to work at 9AM, and end up with no savings of daylight at all. Why don’t I break all my light bulbs and start getting up at 4AM and going to bed at 8PM. That maximizes daylight usage not to mention you see both sunrise and sunset. Sounds good to me. Why doesn’t everybody do that?

mail interception, postal abuse, stamp value

Boy, this one may need a table of contents…

Let’s see, it all started with somebody wondering if you can get a letter back from the postal service once it has been mailed, but before it has been delivered. Maybe you changed your mind about sending the letter, for example. I still don’t know the answer, but I’m guessing if there is no return address on it, forget it. If there is a return address, however, it ought to be possible, right? The sender will get the letter back normally in the case that it is undeliverable, so the sender is essentially a secondary recipient. What does the postal service do with undeliverable mail that has no return address anyway? Shred it? Anyway, this doens’t seem like a satisfactory conclusion in any case, that the return address should play an unrelated role in the mail interception problem.

Which brings me to the second topic. (Read the article)

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