About

I am a Ph.D. candidate in Computer Science at NJIT (Ying Wu College of Computing), advised by Professor Ioannis Koutis. My dissertation research began in graph algorithms, ranking from pairwise comparisons, scheduling, and high-performance computing, and has expanded substantially into machine learning and AI systems — adaptive and budget-aware LLM inference, LLM reasoning and routing, LLM-serving policies, learning-augmented algorithms, and natural-language optimization.

Alongside this research I have built research-oriented software engineering experience in Python and C/C++: optimization-solver-backed experimentation (Gurobi, CPLEX, HiGHS, MiniZinc), HPC/SLURM cluster workflows, GPU experimentation, reproducible evaluation pipelines, and, through an industry internship, production C++/Qt engineering.

I hold a Bachelor's degree in Computer Engineering (Computer Architecture) from Isfahan University of Technology (2015–2020), officially evaluated as equivalent to a U.S. Bachelor of Science in Computer Engineering.

Featured Research

LLM-Serving Scheduler Portfolios

Reproducible evaluation infrastructure for LLM-inference serving schedulers, spanning 120 workload windows, 13 scheduler policies, and 6 calibrated operating regions (9,360 configurations, 18,720 GPU-calibrated simulator executions), with a 240-run real-vLLM/GPU benchmark campaign on SLURM used to check simulator findings against instrumented hardware runs on a selected case. Per-scenario policy selection improved on the best single fixed policy; the project reports this result together with where lighter-weight online selectors fell short, rather than only the positive headline number. This is selected-case hardware validation, not a claim of broad multi-cluster validation.

Budget-Aware LLM Inference & Cost-Aware Reasoning Routing

Two related lines of work on spending a fixed inference budget well: (1) analyzing cost/latency/accuracy tradeoffs for closed-API LLM inference (OpenAI, Gemini) under matched logical-call budgets across GSM8K, MATH-500, GPQA-Diamond, and StrategyQA; and (2) an adaptive, cost-aware routing policy that decides when a cheap LLM answer should be revised versus accepted, evaluated under matched-budget conditions.

Retrieval-Assisted Natural-Language Optimization

A system that maps natural-language descriptions of combinatorial optimization problems to structured LP/ILP formulations, using retrieval-conditioned schema selection, deterministic grounding, and solver-backed validation (SciPy/HiGHS). Evaluated on a 331-query corpus together with the public NLP4LP benchmark and the OptMath external validation domain.

Learning-Augmented Cache Eviction

A trace-driven cache-eviction simulator studying whether predicting finite-horizon downstream miss costs at the candidate level can improve online cache replacement, benchmarked against LRU, SIEVE, FIFO-Reinsertion, and learned baselines (LRB, 3L-Cache, CACHEUS, HALP) across seven workload families. Under the corrected, matched-comparison evaluation protocol, the proposed predictor does not outperform the strongest baselines — the manuscript reports this as a controlled negative/mixed result rather than a claim of superiority. The accompanying LAFC-Evict dataset (v0.3, 22.4M rows of counterfactual eviction-decision supervision) is published on Hugging Face as a public artifact.

Training-Free Ranking & Weighted Feedback Arc Set

Training-free ranking from pairwise comparisons via weighted feedback-arc-set (FAS) and acyclic graph construction (accepted, The Journal of Supercomputing, 2026 — see Publications). Related large-scale-graph work includes an incumbent-protected SCC-neighborhood search and a separate interval-based local-refinement heuristic for the weighted FAS problem, applied to the FlyWire connectome (136,648 neurons, 5.6M+ weighted synapses), reporting the highest forward-weight score published to date on that benchmark.

NJIT Thesis Auditor

A free, local-first tool that audits NJIT thesis/dissertation formatting against Graduate Studies guidelines from a compiled PDF, TeX source tree, or DOCX comments — no external API calls for document analysis. Implements 80+ heuristic checks (TeX hygiene; PDF margins, fonts, spacing, headings, TOC/LOT/LOF structure, page numbering, front matter, and references) behind both a web UI and a CLI, with SSRF-guarded URL fetching, privacy-safe report exports, and a human-feedback workflow for reviewing PDF/DOCX annotations. Backed by 3,192 passing automated tests and green multi-version CI (Python 3.10–3.12), with clean mypy and ruff checks across 113 source files.

Repository is currently private; available on request.

View all projects on GitHub — including consistency-aware LLM-judge reranking and uncertainty-gated graph correction for node classification (see Publications).

Publications

Peer-Reviewed Publications

S. Vahidi. "Training-Free Ranking from Pairwise Comparisons via Acyclic Graph Construction." The Journal of Supercomputing — accepted, in production, 2026 (sole author).
B. Schieber, B. Samineni, S. Vahidi. "Interweaving Real-Time Jobs with Energy Harvesting to Maximize Throughput." Algorithmica, 2025.
M. M. Islam, S. Vahidi, B. Schieber, S. Basu Roy. "Promoting Fairness and Priority in Selecting k-Winners Using IRV." Proceedings of the 30th ACM SIGKDD Conference on Knowledge Discovery and Data Mining (KDD), 2024.
B. Schieber, S. Vahidi. "Approximating Connected Maximum Cuts via Local Search." 31st Annual European Symposium on Algorithms (ESA), 2023.
S. Vahidi, B. Schieber, Z. Du, D. A. Bader. "Parallel Longest Common SubSequence Analysis in Chapel." 27th IEEE High Performance Extreme Computing Conference (HPEC), 2023.
H. Falsafain, M. R. Heidarpour, S. Vahidi. "A Branch-and-Price Approach to a Variant of the Cognitive Radio Resource Allocation Problem." Ad Hoc Networks, vol. 132, 2022.

Preprints & Manuscripts Under Review

S. Vahidi, I. Koutis. "Minimum Weighted Feedback Arc Sets for Ranking from Pairwise Comparisons." arXiv preprint, 2024–2025.
S. Vahidi. "Decision-Aligned Eviction-Value Prediction for Robust Learning-Augmented Caching." Knowledge-Based Systems — second revision (R2 under review). Preprint posted Apr. 2026.
S. Vahidi. "Retrieval-Assisted Instantiation of Natural-Language Optimization Problems." Submitted to SN Computer Science. Preprint posted Mar. 2026.
S. Vahidi. "Nominal Budgets and Realized Resources in Closed-API Large-Language-Model Inference: A Performance Evaluation Protocol." Submitted to Performance Evaluation. Preprint posted Aug. 2026.
S. Vahidi. "When to Revise: Cost-Aware Adaptive Routing for LLM Reasoning." Preprint, posted Apr. 2026.
S. Vahidi. "Uncertainty-Gated Selective Graph Correction for Node Classification." Preprint, posted Mar. 2026.
S. Vahidi, I. Koutis. "Interval-Based Refinement Algorithms for Large-Scale Weighted Feedback Arc Set." Preprint, posted Feb. 2026.
S. Vahidi. "Incumbent-Protected SCC-Neighborhood Search for the Weighted Feedback Arc Set Problem." Preprint, posted Feb. 2026.
S. Vahidi. "Consistency-Aware Reranking via Preference Graph Repair: Structural Gains and Conditional Retrieval Effects." Manuscript in preparation.

Full list on my Google Scholar profile.

Datasets & Research Artifacts

Original research datasets published on my Hugging Face profile.

frontier-allocation-metrics

Per-query cost, latency, and accuracy outcomes for budgeted, closed-API LLM inference (12,300 rows).

llm-serving-scheduler-baselines

Simulation outcome records comparing 12 third-party LLM-serving scheduler baselines against APT-Serve across synthetic and trace-derived stress tests.

mwfas-heuristic-metrics

Metrics-only dataset (7,371 rows, 14 tables) reporting heuristic-algorithm performance on the Minimum Weighted Feedback Arc Set problem.

lafc-evict (v0.3)

22,356,992 rows of derived cache-eviction counterfactual supervision data for learning-augmented caching research.

nl-optimization-instantiation-metrics (v1.2)

Evaluation outcomes for a retrieval-assisted natural-language optimization pipeline on the NLP4LP benchmark and the OptMath validation domain.

View all datasets on Hugging Face — including additional selector-regret, ranking, and LLM-judge-consistency artifacts.

Experience

Software Developer Intern — Canfield Scientific Inc., Parsippany, NJ

Summer 2025 (Jun–Aug 2025)

Contributed to a production C++/Qt dermatology imaging platform. Implemented modules for multi-camera image capture, annotation, lesion tracking, and report generation within an established production codebase; debugged real-time acquisition workflows and image-processing pipelines under production and memory constraints.

Graduate Research Assistant — NJIT

Jan 2022 – Mar 2023

Researched algorithmic and optimization-based approaches for computational problems, including parallel LCS algorithms in Chapel (IEEE HPEC 2023), energy-harvesting-aware real-time scheduling (Algorithmica 2025), and local-search methods for connected maximum cuts (ESA 2023).

Graduate Teaching Assistant — Department of Computer Science, NJIT

Apr 2023 – Present

Supported CS 610 Data Structures and Algorithms (multiple semesters, 2023–2026), DS 677 Deep Learning (Fall 2025), CS 435 Advanced Data Structures (Fall 2025), and CS 388 / CodePath Intermediate Android Development (Spring 2026). Duties included grading, student mentoring, exam support, review of GitHub-based lab and project submissions, repository-access troubleshooting, CodePath/Canvas grading workflows, and building Python-based grading/course automation tools.

Awards & Research Support

Awards

Research Support

Items above are API, compute, and developer credits, not unrestricted cash grants.

Academic Service

Peer Review

Completed 190+ verified peer reviews across artificial intelligence and machine learning, optimization, theoretical computer science, operations research, and parallel computing. Representative venues include Engineering Applications of Artificial Intelligence, Computers & Industrial Engineering, Journal of Combinatorial Optimization, Journal of Scheduling, Theoretical Computer Science, ACM SIGKDD/KDD, and ACM Transactions on Parallel Computing.

Conference Service

Full verified reviewing record: Web of Science.

Resumes

These are resumes, not a full academic CV — an academic CV is not yet available.

Research Resume

For Research Scientist / Applied Scientist / Research Engineer roles. Updated September 2026.

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Engineering/ML Systems Resume

For research-oriented software engineering / ML systems engineering roles. Updated September 2026.

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Contact

Email: sv96@njit.edu