Search Results for author: Hakan Gokcesu

Found 37 papers, 0 papers with code

Sequential Linearithmic Time Optimal Unimodal Fitting When Minimizing Univariate Linear Losses

no code implementations4 Apr 2023 Kaan Gokcesu, Hakan Gokcesu

This paper focuses on optimal unimodal transformation of the score outputs of a univariate learning model under linear loss functions.

A Note On Nonlinear Regression Under L2 Loss

no code implementations30 Mar 2023 Kaan Gokcesu, Hakan Gokcesu

We investigate the nonlinear regression problem under L2 loss (square loss) functions.

regression

Efficient Lipschitzian Global Optimization of Hölder Continuous Multivariate Functions

no code implementations24 Mar 2023 Kaan Gokcesu, Hakan Gokcesu

This study presents an effective global optimization technique designed for multivariate functions that are H\"older continuous.

Formulation of Weighted Average Smoothing as a Projection of the Origin onto a Convex Polytope

no code implementations19 Mar 2023 Kaan Gokcesu, Hakan Gokcesu

Our study focuses on determining the best weight windows for a weighted moving average smoother under squared loss.

A 2-opt Algorithm for Locally Optimal Set Partition Optimization

no code implementations14 Mar 2023 Kaan Gokcesu, Hakan Gokcesu

Our research deals with the optimization version of the set partition problem, where the objective is to minimize the absolute difference between the sums of the two disjoint partitions.

Data Dependent Regret Guarantees Against General Comparators for Full or Bandit Feedback

no code implementations12 Mar 2023 Kaan Gokcesu, Hakan Gokcesu

Our algorithm works from a universal prediction perspective and the performance measure used is the expected regret against arbitrary comparator sequences, which is the difference between our losses and a competing loss sequence.

Multi-Armed Bandits

$1D$ to $nD$: A Meta Algorithm for Multivariate Global Optimization via Univariate Optimizers

no code implementations6 Sep 2022 Kaan Gokcesu, Hakan Gokcesu

In this work, we propose a meta algorithm that can solve a multivariate global optimization problem using univariate global optimizers.

Optimal Tracking in Prediction with Expert Advice

no code implementations7 Aug 2022 Hakan Gokcesu, Suleyman S. Kozat

We study the prediction with expert advice setting, where the aim is to produce a decision by combining the decisions generated by a set of experts, e. g., independently running algorithms.

Decision Making

An Auto-Regressive Formulation for Smoothing and Moving Mean with Exponentially Tapered Windows

no code implementations29 Jun 2022 Kaan Gokcesu, Hakan Gokcesu

We investigate an auto-regressive formulation for the problem of smoothing time-series by manipulating the inherent objective function of the traditional moving mean smoothers.

Time Series Time Series Analysis

Efficient Minimax Optimal Global Optimization of Lipschitz Continuous Multivariate Functions

no code implementations6 Jun 2022 Kaan Gokcesu, Hakan Gokcesu

In this work, we propose an efficient minimax optimal global optimization algorithm for multivariate Lipschitz continuous functions.

A Log-Linear Time Sequential Optimal Calibration Algorithm for Quantized Isotonic L2 Regression

no code implementations1 Jun 2022 Kaan Gokcesu, Hakan Gokcesu

We study the sequential calibration of estimations in a quantized isotonic L2 regression setting.

regression

Robust, Nonparametric, Efficient Decomposition of Spectral Peaks under Distortion and Interference

no code implementations18 Apr 2022 Kaan Gokcesu, Hakan Gokcesu

We propose a decomposition method for the spectral peaks in an observed frequency spectrum, which is efficiently acquired by utilizing the Fast Fourier Transform.

Second Order Regret Bounds Against Generalized Expert Sequences under Partial Bandit Feedback

no code implementations13 Apr 2022 Kaan Gokcesu, Hakan Gokcesu

We study the problem of expert advice under partial bandit feedback setting and create a sequential minimax optimal algorithm.

Blind Source Separation for Mixture of Sinusoids with Near-Linear Computational Complexity

no code implementations27 Mar 2022 Kaan Gokcesu, Hakan Gokcesu

We propose a multi-tone decomposition algorithm that can find the frequencies, amplitudes and phases of the fundamental sinusoids in a noisy observation sequence.

blind source separation

Merging Knockout and Round-Robin Tournaments: A Flexible Linear Elimination Tournament Design

no code implementations22 Mar 2022 Kaan Gokcesu, Hakan Gokcesu

We propose a new tournament structure that combines the popular knockout tournaments and the round-robin tournaments.

Natural Hierarchical Cluster Analysis by Nearest Neighbors with Near-Linear Time Complexity

no code implementations15 Mar 2022 Kaan Gokcesu, Hakan Gokcesu

We propose a nearest neighbor based clustering algorithm that results in a naturally defined hierarchy of clusters.

Clustering

A Linearithmic Time Locally Optimal Algorithm for the Multiway Number Partition Optimization

no code implementations10 Mar 2022 Kaan Gokcesu, Hakan Gokcesu

We study the problem of multiway number partition optimization, which has a myriad of applications in the decision, learning and optimization literature.

Smoothing with the Best Rectangle Window is Optimal for All Tapered Rectangle Windows

no code implementations6 Mar 2022 Kaan Gokcesu, Hakan Gokcesu

We show that the best rectangle window is optimal for such window definitions.

Low Regret Binary Sampling Method for Efficient Global Optimization of Univariate Functions

no code implementations18 Jan 2022 Kaan Gokcesu, Hakan Gokcesu

For a search space of $[0, 1]$, our approach has at most $L\log (3T)$ and $2. 25H$ regret for $L$-Lipschitz continuous and $H$-Lipschitz smooth functions respectively.

Efficient, Anytime Algorithms for Calibration with Isotonic Regression under Strictly Convex Losses

no code implementations31 Oct 2021 Kaan Gokcesu, Hakan Gokcesu

We start by studying the traditional square error setting with its weighted variant and show that the optimal monotone transform is in the form of a unique staircase function.

regression

Near-Linear Time Algorithm with Near-Logarithmic Regret Per Switch for Mixable/Exp-Concave Losses

no code implementations28 Sep 2021 Kaan Gokcesu, Hakan Gokcesu

We investigate the problem of online learning, which has gained significant attention in recent years due to its applicability in a wide range of fields from machine learning to game theory.

Generalized Translation and Scale Invariant Online Algorithm for Adversarial Multi-Armed Bandits

no code implementations19 Sep 2021 Kaan Gokcesu, Hakan Gokcesu

We study the adversarial multi-armed bandit problem and create a completely online algorithmic framework that is invariant under arbitrary translations and scales of the arm losses.

Multi-Armed Bandits Translation

A Quadratic Time Locally Optimal Algorithm for NP-hard Equal Cardinality Partition Optimization

no code implementations16 Sep 2021 Kaan Gokcesu, Hakan Gokcesu

We study the optimization version of the equal cardinality set partition problem (where the absolute difference between the equal sized partitions' sums are minimized).

Efficient Locally Optimal Number Set Partitioning for Scheduling, Allocation and Fair Selection

no code implementations10 Sep 2021 Kaan Gokcesu, Hakan Gokcesu

We study the optimization version of the set partition problem (where the difference between the partition sums are minimized), which has numerous applications in decision theory literature.

Scheduling

Nonparametric Extrema Analysis in Time Series for Envelope Extraction, Peak Detection and Clustering

no code implementations5 Sep 2021 Kaan Gokcesu, Hakan Gokcesu

In this paper, we propose a nonparametric approach that can be used in envelope extraction, peak-burst detection and clustering in time series.

Clustering Time Series +1

Cumulative Regret Analysis of the Piyavskii--Shubert Algorithm and Its Variants for Global Optimization

no code implementations24 Aug 2021 Kaan Gokcesu, Hakan Gokcesu

For $L$-Lipschitz continuous functions, we show that the cumulative regret is $O(L\log T)$.

Optimally Efficient Sequential Calibration of Binary Classifiers to Minimize Classification Error

no code implementations19 Aug 2021 Kaan Gokcesu, Hakan Gokcesu

In this work, we aim to calibrate the score outputs of an estimator for the binary classification problem by finding an 'optimal' mapping to class probabilities, where the 'optimal' mapping is in the sense that minimizes the classification error (or equivalently, maximizes the accuracy).

Binary Classification

Optimal and Efficient Algorithms for General Mixable Losses against Switching Oracles

no code implementations13 Aug 2021 Kaan Gokcesu, Hakan Gokcesu

The best dynamic estimation sequence that we compete against is selected in hindsight with full observation of the loss functions and is allowed to select different optimal estimations in different time intervals (segments).

Recursive Experts: An Efficient Optimal Mixture of Learning Systems in Dynamic Environments

no code implementations19 Sep 2020 Kaan Gokcesu, Hakan Gokcesu

By exploiting this relation, specific learning systems can be designed that perform asymptotically optimal for various applications.

Decision Making

A Generalized Online Algorithm for Translation and Scale Invariant Prediction with Expert Advice

no code implementations9 Sep 2020 Kaan Gokcesu, Hakan Gokcesu

In this work, we aim to create a completely online algorithmic framework for prediction with expert advice that is translation-free and scale-free of the expert losses.

Translation

Minimax Optimal Algorithms for Adversarial Bandit Problem with Multiple Plays

no code implementations25 Nov 2019 N. Mert Vural, Hakan Gokcesu, Kaan Gokcesu, Suleyman S. Kozat

To construct our algorithm, we introduce a new expert advice algorithm for the multiple-play setting.

Universal Online Convex Optimization with Minimax Optimal Second-Order Dynamic Regret

no code implementations30 Jun 2019 Hakan Gokcesu, Suleyman S. Kozat

Our approach can compete against all comparator sequences simultaneously (universally) in a minimax optimal manner, i. e. each regret guarantee depends on the respective comparator path variation.

Accelerating Min-Max Optimization with Application to Minimal Bounding Sphere

no code implementations29 May 2019 Hakan Gokcesu, Kaan Gokcesu, Suleyman Serdar Kozat

We study the min-max optimization problem where each function contributing to the max operation is strongly-convex and smooth with bounded gradient in the search domain.

Minimax Optimal Online Stochastic Learning for Sequences of Convex Functions under Sub-Gradient Observation Failures

no code implementations19 Apr 2019 Hakan Gokcesu, Suleyman S. Kozat

We specifically study scenarios where our sub-gradient observations can be noisy or even completely missing in a stochastic manner.

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