Martin Keller-Ressel Profile
Martin Keller-Ressel

@mkellerressel

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https://t.co/ljnj8YWOgK | Professor at TU Dresden | Stochastics/Probability, Financial Mathematics, Networks, Hyperbolic Geometry.

Dresden, Sachsen
Joined June 2009
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@mkellerressel
Martin Keller-Ressel
11 months
These bounds enable us to quantify the interplay between optimization hyperparameters and the tail-index. Doing so, we contribute to the discussion on links between heavy tails and the generalization performance of neural networks. Find our paper here:
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@mkellerressel
Martin Keller-Ressel
11 months
💻 We give explicit upper and lower bounds on the tail-index of the resulting parameter distribution and validate these bounds in numerical experiments. 5/6
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@mkellerressel
Martin Keller-Ressel
11 months
🧮 In our paper, we analyze a continuous diffusion approximation of SGD and show mathematically (in a regularized linear regression framework) that it leads to an asymptotically heavy-tailed parameter distribution, even though local gradient noise is Gaussian. 4/6
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@mkellerressel
Martin Keller-Ressel
11 months
📄 It has repeatedly been observed that loss minimization by stochastic gradient descent (SGD) leads to heavy-tailed distributions of neural network parameters. 3/6
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@mkellerressel
Martin Keller-Ressel
11 months
👉 TL;DR: Heavy tailed parameter distributions can emerge from locally Gaussian gradient noise, as we show both theoretically and empirically. 2/6
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@mkellerressel
Martin Keller-Ressel
11 months
On my way to represent @Sca_DS at #NeurIPS2024 and to present a poster on joint work with Zhe Jiao on "Emergence of Heavy Tails in Homogenized Stochastic Gradient Descent" 1/6
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@carolecadwalla
Carole Cadwalladr
1 year
Please read this. It's literally been 8 years in the writing. The first wave of tech disruption of democracy 2016-2024 is over. What starts now is something much, much worse: the age of information chaos. 1/ https://t.co/bsnKnag51p
Tweet card summary image
theguardian.com
The era that began with the Great Disruptor’s first term is over. Beware the emerging elite
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@MathMatize
MathMatize Memes
1 year
Of course
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@LongFormMath
Jay Cummings
1 year
Isaac Newton has verified his email on Google Scholar. And has recently picked up a professorship at MIT. Good for him.
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@DulwichQuantum
Dulwich Quantum Computing
1 year
Will be disappointed if the Nobel Prize in literature doesn't go to ChatGPT for being the most prolific author.
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@kareem_carr
🔥 Dr Kareem Carr 🔥
1 year
nobody: nobel prize committee: the method of least squares was invented to do astrophysics so linear regression is technically physics
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@yoavgo
(((ل()(ل() 'yoav))))👾
1 year
even if we agree that hopfield networks and boltzman machines are super-important in ML / DL / NN (I don't), calling them "inventions that *enable* machine learning with neural networks" is really a huge stretch. ML/DL/NN owes a ton to Hinton, but this ain't it.
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@mkellerressel
Martin Keller-Ressel
1 year
It was awarded “for extremely interesting results in the framework of the 2-factor Vasicek model using the concept of envelopes of curves and their associated winding number, which help to address several questions of practical interest related to the shape of [...] yield curves”
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@mkellerressel
Martin Keller-Ressel
1 year
😁 I am thrilled to announce that my paper "State Space Decomposition and Classification of Term Structure Shapes in the Two-Factor Vasicek Model" with Felix Sachse has won the 2023 Best Paper Award of the International Journal of Theoretical and Applied Finance @ws_ijtaf
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@mkellerressel
Martin Keller-Ressel
1 year
To summarize, I can see why some people say that 'negative probabilities are used in financial math'. However, many people (like me) would disagree, because in 99% of cases you want an arbitrage-free model and in the other 1% you would not call Q' a `probability measure'
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@mkellerressel
Martin Keller-Ressel
1 year
Another thing is that Q (and Q') are not physical/statistical probability meas in the sense that they tell you 'an event A will happen (or is estimated to happen) with a probability Q(A)' but instead are 'pricing tools' for assets, employed only through taking expectations. 6/7
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@mkellerressel
Martin Keller-Ressel
1 year
There is a big problem with such models: If you have arbitrage *and* a linear pricing rule, crazy things happen: You can construct financial contracts, where you get paid $1 million to enter into the contract and get another guaranteed payout of $1 million at expiry. 5/7
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@mkellerressel
Martin Keller-Ressel
1 year
Now if you allow for arbitrage (riskless profits) in your market model, then, instead of your probability measure Q you may have a signed measure Q' ('negative probabilities'), such that asset prices are discounted expectations under Q'. 4/7
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@mkellerressel
Martin Keller-Ressel
1 year
This probability measure Q is distinct from the statistical measure P, which is used for prediction. The measure Q is a purely 'mathematical' construct for the consistent pricing of options.. 3/7
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