Kimon Fountoulakis
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kfountou.bsky.social
Kimon Fountoulakis
@kfountou.bsky.social
Associate Professor at CS UWaterloo
Machine Learning
Lab: opallab.ca
I mean, it makes sense. If sky-net rules over everything, then Prince Harry will not be prince anymore.
October 22, 2025 at 10:33 PM
Yes
October 19, 2025 at 1:17 AM
3. This allows us to compute the eigenvalues of the Fourier transform exactly, and hence its spectral norm.

Furthermore, we show that the mixing time of the random walk for our family is tight.
October 18, 2025 at 9:38 PM
2. Remarkably, this Fourier transform is governed entirely by the standard representation of the group. Using tools from group and representation theory, the entire analysis collapses to that single representation.
October 18, 2025 at 9:38 PM
Main proof technique.

We couple two machines from this family as a random walk on the group S_n x S_n and show that, with high probability, they are indistinguishable. How?

1. Indistinguishability is controlled by the spectral norm of the Fourier transform of the walk’s single-step distribution.
October 18, 2025 at 9:38 PM
We construct a large randomized family of shuffling machines. Each machine shuffles its input using only transpositions. By flipping a random coin to decide whether to apply or ignore each transposition, we obtain a randomized family with the desired properties.
October 18, 2025 at 9:38 PM
We show that SQ hardness can be established when both the alphabet size and input length are polynomial in the number of states.
October 18, 2025 at 9:38 PM
We prove the first SQ hardness result for learning semiautomata under the uniform distribution over input words and initial states, without relying on parity gadgets or adversarial inputs. The hardness is structural, it arises purely from the transition structure, not from hard languages.
October 18, 2025 at 9:38 PM
Done.
June 9, 2025 at 3:11 PM
2) Can a neural network discover instructions for performing multiplication itself?

The answer to the first question is yes, with high probability and up to some arbitrary, predetermined precision (see the quoted post).
May 27, 2025 at 12:35 AM
Learning to execute arithmetic exactly, with high probability, can be quite expensive. In the plot, 'ensemble complexity' refers to the number of independently trained models required to achieve exact learning with high probability. ell is the number of bits per number in the input.
May 26, 2025 at 3:21 AM
Learning to execute arithmetic exactly, with high probability, can be quite expensive. In the plot, 'ensemble complexity' refers to the number of independently trained models required to achieve exact learning with high probability. ell is the number of bits per number in the input.
May 26, 2025 at 3:19 AM
I never understood the point of trams. They're slow and expensive. I've been to two cities that built them while I was there, Edinburgh and Athens, and in both cases, the projects were born out of corruption. Especially in Edinburgh, it was a disaster. en.wikipedia.org/wiki/Edinbur...
Edinburgh Tram Inquiry - Wikipedia
en.wikipedia.org
May 21, 2025 at 2:39 PM
Thanks, the connection to formal languages is quite interesting. I have a section in the repo regarding formal languages but it's small mainly because it's not a topic that I am familiar with. I will add them!
May 17, 2025 at 11:49 AM