CV

General Information

Full Name Hardik Tankaria, PhD
Research Areas Mathematical Optimization; Optimization for Machine Learning; Second-Order and Stochastic Methods; Randomized Numerical Linear Algebra; Constrained and Multi-Objective Bayesian Optimization; Knowledge Representation for Scientific Machine Learning; Heuristic Search and Planning for Combinatorial Discovery; Federated and Communication-Efficient Distributed Optimization
Current Role Machine Learning Research Engineer, MI-6 Co., Ltd., Tokyo
Location Kyoto, Japan
Email hardiktankaria1406@gmail.com
Website https://hardy-opt.github.io
GitHub https://github.com/hardy-opt
Google Scholar https://scholar.google.com/citations?user=Tx4DHMQAAAAJ
Languages Gujarati (native), Hindi (native), English (business), Japanese (beginner)

Profile

  • I build optimization algorithms for large-scale machine learning and take them from a convergence proof to a benchmarked implementation. PhD in Informatics (Mathematical Optimization) from Kyoto University, with published work on second-order and variance-reduced methods that make curvature information affordable at high dimension. Currently project owner for three concurrent R&D lines at MI-6 Co., Ltd., spanning search heuristics for computer-aided synthesis planning, budget-aware Bayesian optimization for autonomous experimentation, and interface engineering between machine learning subsystems. Interested in research scientist and research engineer roles where mathematical optimization is the substance of the work.

Education

  • Apr 2018 - Mar 2024
    PhD in Informatics (Mathematical Optimization)
    Kyoto University, Graduate School of Informatics, Dept. of Applied Mathematics & Physics
    • Doctoral research areas: mathematical optimization; optimization for machine learning; second-order and stochastic methods; randomized numerical linear algebra
    • Thesis: The Utilization of Second-Order Information for Large-Scale Unconstrained Optimization Problems (PDF)
    • Doctoral study funded by the Japan International Cooperation Agency (JICA)
    • GPA: 3.7/4.0
  • Oct 2017 - Mar 2018
    Research Student, Mathematical Optimization
    Kyoto University, Graduate School of Informatics
    • System Optimization Laboratory
  • Aug 2014 - May 2016
    MSc, Mathematics
    Indian Institute of Technology Hyderabad
    • Thesis: Hasse-Minkowski Principle for Quadratic Forms over Q
    • Admitted via the Joint Admission Test (JAM), all-India rank 343
  • Jul 2011 - May 2014
    BSc, Mathematics
    Saurashtra University, D.K.V. Arts & Science College, Jamnagar

Experience

  • Nov 2025 - present
    Machine Learning Research Engineer
    MI-6 Co., Ltd., Tokyo, Japan
    • Project owner for three concurrent R&D lines in optimization and AI for science.
    • Budget-aware Bayesian optimization for autonomous experimentation: a closed-loop harness in which every proposed experiment is priced, charged against a budget, and refused if unaffordable, so policy quality is always reported beside spend. Twelve proposal policies, three acquisition optimizers, and a one-command reproducibility check that re-derives every committed figure from committed data.
    • Search heuristics for computer-aided synthesis planning: a learned cost-to-go estimate reused to reorder candidate reactions by remaining distance to available starting materials, improving solve rate and reducing search effort at unchanged per-step compute. First-author conference abstract.
    • An installable, versioned software component publishing a data contract to a separate optimization engine, with determinism enforced as a test, module boundaries checked at process level, and continuous integration gating its own published result counts.
    • Methodology across all three: pre-registered experiment designs, paired statistical tests with bootstrap confidence intervals, a stated detection floor beside every comparison, and negative results reported with their mechanism.
  • Aug 2025 - Nov 2025
    Machine Learning Research Intern
    MI-6 Co., Ltd., Tokyo, Japan
    • Built a neural-guided bidirectional search method for double-ended synthesis planning, extending a published planner to handle convergent routes via a multi-tree forest and a proof-tree-complete meeting criterion.
    • Implemented Monte Carlo Tree Search with UCT and PUCT variants and graph-based heuristics for retrosynthetic pathway search; benchmarked against established baselines over public chemical databases.
    • Built multi-objective scoring for route selection across path length, cost and yield.
  • Jan 2025 - Mar 2025
    Machine Learning Research Associate
    Indian Institute of Technology Mandi, India
    • Developed a Nystrom-based ADMM algorithm for federated learning, targeting the communication and memory cost of second-order information in distributed training.
    • Built a Python framework for decentralised training across multiple nodes, with convergence monitoring and benchmarking.
    • Co-PI; guided two M.Tech researchers. Delivered an invited talk on the method.
  • Dec 2021 - Mar 2023
    Research Assistant
    Dept. of Intelligence Science & Technology, Kyoto University
    • Developed the regularized Nystrom method for large-scale optimization, reducing per-iteration cost from O(nd^2 + d^3) to O(ndm + dm^2) with sketch size m of roughly 5-20% of the feature dimension, and established global convergence under standard assumptions.
    • Benchmarked against randomized subspace Newton and Newton-sketch on high-dimensional classification.
    • Applied curvature-aware optimization to brain-MRI tumour classification with transfer learning.
  • May 2021 - Oct 2024
    E-Commerce & Marketing Research Analyst (part-time)
    Hayakawa Co. Ltd., Kyoto, Japan
    • Held alongside doctoral research. Managed B2B client relationships and negotiations for international e-commerce, conducted competitive analysis for listings and pricing, and automated sales and inventory reporting.

Publications

  • A Regularized Limited Memory BFGS Method for Large-Scale Unconstrained Optimization and its Efficient Implementations
    • Computational Optimization and Applications 82(1), 61-88 (2022). doi:10.1007/s10589-022-00351-5

    • Hardik Tankaria, Shinji Sugimoto, Nobuo Yamashita

  • A Stochastic Variance Reduced Gradient using Barzilai-Borwein Techniques as Second Order Information
    • Journal of Industrial and Management Optimization 20(2), 525-547 (2024). doi:10.3934/jimo.2023089

    • Hardik Tankaria, Nobuo Yamashita

  • NysReg-Gradient: Regularized Nystrom-Gradient for Large-Scale Unconstrained Optimization and its Application
    • IEEE IJCNN 2026 (WCCI), Maastricht

    • Hardik Tankaria, Makoto Yamada, Dinesh Singh

  • Nys-Fed: Communication and Memory Efficient Nystrom Approximated Curvature for Federated Learning
    • IEEE IJCNN 2026 (WCCI), Maastricht

    • Sagnik Ghosh, Hardik Tankaria, Arnav Bhavsar, Varun Dutt, Dinesh Singh

  • Nys-Newton: Nystrom-Approximated Curvature for Convex Optimization
    • IEICE Technical Report (IBISML) 122(325), 134-141 (2022)

    • Hardik Tankaria, Dinesh Singh, Makoto Yamada

Preprints

  • Regularized Nystrom Method for Large-Scale Unconstrained Non-Convex Optimization
    • Hardik Tankaria (2024)

  • Nys-curve: Nystrom-Approximated Curvature for Stochastic Optimization
    • Hardik Tankaria, Dinesh Singh, Makoto Yamada. arXiv:2110.08577 (2021)

Funding & Awards

  • Apr 2019 - Mar 2020
    Co-investigator, Encouragement Research Grant (1,000,000 JPY)
    KIOXIA
    • Project: RL-BFGS for Big Data with Improved Global Convergence.
    • Named co-investigator on an industry-funded grant as a second-year PhD student; responsible for numerical simulations and convergence analysis of the proposed regularized L-BFGS method.
  • 2017
    JICA Scholarship for Doctoral Study
    Japan International Cooperation Agency
    • Full funding for doctoral study at Kyoto University.
  • 2017
    GSET - Gujarat State Eligibility Test
    Government of Gujarat, India
    • Qualified for Assistant Professor eligibility in state universities.
  • 2015
    Merit-cum-Means Scholarship
    IIT Hyderabad
  • 2014
    Joint Admission Test (JAM) - All-India Rank 343
    Indian Institutes of Technology

Service & Leadership

  • 2022 - present
    Reviewer
    ICML, IJCNN, ICASSP, ICDCIT
  • Jan 2025 - Mar 2025
    Co-PI, Federated Learning project
    Indian Institute of Technology Mandi, India
    • Guided two M.Tech researchers.
  • 2025 - present
    Vice President
    Japan Chapter, Indian Institute of Technology Hyderabad (IIT Hyderabad) Alumni Association
    • Core member of the Executive Committee, responsible for institutional and community partnerships, including academia-industry collaboration between the institute and organisations in Japan.
  • 2022 - 2024
    President (Treasurer 2019-2022)
    Indian Association of Kyoto
    • Led a volunteer team organising cultural events for 200+ participants, including visits by the Mayor of Kyoto, the Consulate General of India in Osaka-Kobe, and members of the Japanese House of Representatives.

Technical Skills

  • Programming
    • Python (expert)

    • MATLAB

    • C++ (basic)

    • SQL

    • LaTeX

  • Optimization
    • Convex and non-convex optimization

    • Second-order and quasi-Newton methods (L-BFGS, Newton-sketch, Nystrom approximation)

    • Stochastic and variance-reduced methods (SGD, SVRG, Adam)

    • Randomized numerical linear algebra

    • Convergence and complexity analysis

    • Multi-objective and hyperparameter optimization

  • Supervised learning
    • Classification and regression: logistic regression, linear and L2-regularized models, support vector machines (hinge and squared hinge)

    • Random forests, gradient boosting (XGBoost, LightGBM), stacked ensembles

    • Feature engineering, exploratory analysis, data preprocessing

    • Class-imbalance handling (SMOTE, class weighting) and cost-sensitive objectives

    • Model selection and evaluation: cross-validation, ROC-AUC, precision/recall, F1, confusion matrices

    • Model interpretability (SHAP, feature importance)

  • Deep learning
    • Convolutional networks (ResNet) and recurrent networks (LSTM)

    • Transfer learning and fine-tuning

    • CNN encoders for surrogate models

    • Curvature-aware training of deep networks

    • Medical image classification

  • Bayesian and probabilistic methods
    • Bayesian optimization and Gaussian processes

    • Acquisition function design

    • Cost-aware and multi-fidelity acquisition

    • Sequential decision-making under a budget

  • Federated and distributed learning
    • Federated learning across edge clients, benchmarked against FedAvg, FedProx, FedAdam, FedNew, FedNS and DONE

    • ADMM and one-pass ADMM

    • Communication- and memory-efficient second-order updates

    • Quantization of client updates

    • Decentralised training frameworks

  • Search and planning
    • Shortest-path and best-first search with learned heuristics: A, bidirectional A with meeting-point selection

    • Monte Carlo Tree Search with UCT and PUCT variants

    • AND/OR graph search and cost-to-go value functions

    • Branch-selection heuristics to reduce search expansions

    • Multi-objective route scoring

  • AI systems and agentic architectures
    • LLM agents with knowledge grounding and tool use

    • Sub-agent architectures communicating through versioned data contracts

    • Cost-aware and multi-fidelity decision agents

    • Evaluation of LLM components with pre-registered predictions, positive controls and instrument-validity gates

  • AI-assisted engineering
    • Claude Code and Codex in the development and review loop

    • Independent re-derivation of published results by a separate agent

    • AI-assisted refactoring, test generation and documentation

  • Libraries
    • PyTorch, NumPy, SciPy, scikit-learn, pandas

    • BoTorch, GPyTorch, Optuna

    • Gurobi

    • RDKit, MONAI, NiBabel

  • Research engineering
    • Reproducible research (determinism tests, CI-gated results)

    • Architecture decision records

    • Experimental design and pre-registration

    • Paired statistical testing (McNemar, bootstrap confidence intervals) and stated detection floors

    • Benchmark and dataset generation with multi-stage validation

  • Platforms and tools
    • Linux, macOS

    • Git, GitHub Actions, pytest, Python packaging, conda

    • Google Colab, Google Cloud Platform

    • MS Office including Excel (VBA, pivot tables)