no code implementations • 31 Mar 2024 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Sihan Liu, Nikos Zarifis
We study the efficient learnability of low-degree polynomial threshold functions (PTFs) in the presence of a constant fraction of adversarial corruptions.
no code implementations • 27 Dec 2023 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
In contrast, algorithms that rely only on random examples inherently require $d^{\mathrm{poly}(1/\epsilon)}$ samples and runtime, even for the basic problem of agnostically learning a single ReLU or a halfspace.
no code implementations • 8 Oct 2023 • Constantine Caramanis, Dimitris Fotakis, Alkis Kalavasis, Vasilis Kontonis, Christos Tzamos
Deep Neural Networks and Reinforcement Learning methods have empirically shown great promise in tackling challenging combinatorial problems.
no code implementations • 6 Aug 2023 • Ilias Diakonikolas, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
In contrast, under a worst- or random-ordering, the number of mistakes must be at least $\Omega(d \log n)$, even when the points are drawn uniformly from the unit sphere and the learner only needs to predict the labels for $1\%$ of them.
no code implementations • NeurIPS 2023 • Vasilis Kontonis, Fotis Iliopoulos, Khoa Trinh, Cenk Baykal, Gaurav Menghani, Erik Vee
Knowledge distillation with unlabeled examples is a powerful training paradigm for generating compact and lightweight student models in applications where the amount of labeled data is limited but one has access to a large pool of unlabeled data.
no code implementations • 13 Oct 2022 • Fotis Iliopoulos, Vasilis Kontonis, Cenk Baykal, Gaurav Menghani, Khoa Trinh, Erik Vee
Our method is hyper-parameter free, data-agnostic, and simple to implement.
no code implementations • 17 Jun 2022 • Ilias Diakonikolas, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
For the ReLU activation, we give an efficient algorithm with sample complexity $\tilde{O}(d\, \polylog(1/\epsilon))$.
no code implementations • 22 Aug 2021 • Dimitris Fotakis, Alkis Kalavasis, Vasilis Kontonis, Christos Tzamos
Our main algorithmic result is that essentially any problem learnable from fine grained labels can also be learned efficiently when the coarse data are sufficiently informative.
no code implementations • 19 Aug 2021 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
We study the general problem and establish the following: For $\eta <1/2$, we give a learning algorithm for general halfspaces with sample and computational complexity $d^{O_{\eta}(\log(1/\gamma))}\mathrm{poly}(1/\epsilon)$, where $\gamma =\max\{\epsilon, \min\{\mathbf{Pr}[f(\mathbf{x}) = 1], \mathbf{Pr}[f(\mathbf{x}) = -1]\} \}$ is the bias of the target halfspace $f$.
no code implementations • 10 Feb 2021 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
We study the problem of agnostically learning halfspaces under the Gaussian distribution.
no code implementations • 1 Dec 2020 • Vasilis Kontonis, Sihan Liu, Christos Tzamos
Our main result is that by training the Generator together with a Discriminator according to the Stochastic Gradient Descent-Ascent iteration proposed by Goodfellow et al. yields a Generator distribution that approaches the target distribution of $f_*$.
no code implementations • 4 Oct 2020 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
{\em We give the first polynomial-time algorithm for this fundamental learning problem.}
no code implementations • 22 Jun 2020 • Ilias Diakonikolas, Daniel M. Kane, Vasilis Kontonis, Nikos Zarifis
For the case of positive coefficients, we give the first polynomial-time algorithm for this learning problem for $k$ up to $\tilde{O}(\sqrt{\log d})$.
no code implementations • 11 Jun 2020 • Ilias Diakonikolas, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
In the Tsybakov noise model, each label is independently flipped with some probability which is controlled by an adversary.
no code implementations • NeurIPS 2020 • Ilias Diakonikolas, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
We study the problem of agnostically learning homogeneous halfspaces in the distribution-specific PAC model.
no code implementations • 13 Feb 2020 • Ilias Diakonikolas, Vasilis Kontonis, Christos Tzamos, Nikos Zarifis
We study the problem of learning halfspaces with Massart noise in the distribution-specific PAC model.
no code implementations • 2 Aug 2019 • Vasilis Kontonis, Christos Tzamos, Manolis Zampetakis
Our main result is a computationally and sample efficient algorithm for estimating the parameters of the Gaussian under arbitrary unknown truncation sets whose performance decays with a natural measure of complexity of the set, namely its Gaussian surface area.
no code implementations • 18 Jul 2017 • Dimitris Fotakis, Vasilis Kontonis, Piotr Krysta, Paul Spirakis
The $k$'th power of this distribution, for $k$ in a range $[m]$, is the distribution of $P_k = \sum_{i=1}^n X_i^{(k)}$, where each Bernoulli random variable $X_i^{(k)}$ has $\mathbb{E}[X_i^{(k)}] = (p_i)^k$.