467 karma · joined January 19, 2012
The determinant is uniquely determined by the following two axioms:
1. The determinant of the "multiply by lambda" operation on a one-dimensional vector space is lambda. 2. If you have a linear operator T on a vector space V, and a T-invariant subspace W, the determinant of T is the product of the determinant of T restricted to W and the determinant of the operator that T induces on the quotient space V / W.
This actually kinda intuitively meshes with the volume-stretching property: if you are stretching the volume by the factor lambda_1 along one subspace and by the factor lambda_2 along some complementary subspace, clearly the overall stretch factor is lambda_1 * lambda_2.
If you aren't working over an algebraically closed field, you can just tensor with the algebraic closure of whatever field you're working with and take the determinant there. There is also a way of adapting the definition so you don't have to do this, but it makes axiom (1) a bit more complicated.
Another bonus is this definition makes the Cayley-Hamilton theorem completely trivial.
Also, you can give an analogous definition of the trace if you replace multiplication with addition, and of the characteristic polynomial if you replace lambda in axiom 1 with x - lambda.
Like tekromancr was getting at, you get a logical contradiction if you assume the existence of 1/0, if you also assume the ring axioms. To elaborate, if 0x = 1, then 0 = 1. It is also an axiom that 0 != 1, and even if you abandon this axiom you only get one extra ring that only has one element. Boring!
You also get a logical contradiction if you add a square root of -1, if you are assuming, say, the ordered ring axioms. But you can lose the order structure and then there is no more contradiction.
If you want to add a new number x with 0x = 1, then you also need to propose how one might alter the notion of a ring so that you don't get a logical contradiction, and you are still left with something interesting. Just like how we altered the notion of an ordered ring, by removing the ordering, so that you don't get a contradiction when adding a square root of -1.
So the crucial difference is, as far as I know, nobody has succeeded in doing this when it comes to division by zero.
Good thing they asked exclusively math professors for a response, so you know you are getting an authoritative answer from someone with many years of training and deep knowledge about the topic. LOL
This seems like a straw man to me. The article never claimed that math is not necessary for the development of machine learning frameworks. In fact, it explicitly states the opposite:
"First of all, math is particularly important if you’re doing machine learning research in an academic setting."
"In particular, there are people at companies like Google and Facebook who are pushing the boundaries of machine learning – people working on bleeding edge tools. These people almost certainly employ calculus, linear algebra, and more advanced math routinely in their work."
I would even speculate that how interesting / boring you find something is not static, but that otherwise boring things can start to seem interesting once it's clear that they are relevant to something you want to achieve.
Personally I learnt math mostly from self-study, and I've learnt it well enough that I now have published research (see [1], also [2] is in review and has been recommended for acceptance with revisions by the referee), have been invited to give talks about my research [3][4][5], and have stayed for a few months as a visiting researcher at University of Muenster [6]. I don't consider myself as having a lot of self-discipline; I have a tendency to hit the snooze button many times, to overeat, to let my room get messy, etc. But once I have an idea, I want to flesh it out and share it with other people, which motivates me to do the things that are necessary for this, which are sometimes boring.
[1] http://content.algebraicgeometry.nl/2017-2/2017-2-007.pdf
[2] https://arxiv.org/abs/1612.07306
[3] https://www.uni-muenster.de/FB10srvi/HotNews/show_artikel.ph...
[4] http://www2.math.binghamton.edu/p/seminars/arit/arit_spring2...
[5] http://www2.math.binghamton.edu/p/seminars/arit/arit_fall201...
[6] https://web.archive.org/web/20170121000748/https://wwwmath.u...
Even if the statement "lack of beating between overtones sounds good" doesn't hold true as a universal rule (and I'm sure this has occurred to many people prior to Wilkerson), you can really see what Helmholtz was getting at here.
Sure, actually it seems highly unlikely to me that they were designed without considering at all how they brain works. Let me clarify what I meant: given the definition of how a Boltzmann machine infers (i.e. how to determine which neurons are on or off), the training algorithm can be derived from purely mathematical considerations.
The training algorithm for Boltzmann machines has two phases:
1. (Awake phase) Feed the network training data, and increase the weights between neurons that tend to get activated simultaneously in this phase.
2. (Dreaming phase) Let the network run without any training input, and decrease the weights between neurons that tend to get activated simultaneously in this phase.
This training algorithm wasn’t designed to emulate how human brains work, it just sort of falls out of the math. And yet (1) resembles the Hebbian principle from neuroscience (neurons that fire together, wire together), and (2) resembles the process described in this article. Actually I suspect something stronger than what the article claims based on this: that the connections that get pruned are the ones connecting neurons that fire together while dreaming. It would be nice to have someone who knows stuff about neuroscience comment on this.
You wouldn't consider the analogue of the Riemann hypothesis for the zeta function of a smooth projective variety over a finite field, proven by Deligne, to be a compelling reason to believe the RH is true?
I don't think that is the right question. Say it produces more knowledge, but the fields that are studied are selected, not by how intrinsically interesting they are, but instead by how much low-hanging fruit they have. I don't think that would necessarily be an improvement.
Or the total number of lines of code in a sequence of programs, where the first program generates a proof of the original theorem, and every other program generates a proof that the preceding program halts, PLUS the size of a proof that the final program halts.