I am a Senior Researcher in Microsoft Azure. Some of my current activities at Microsoft include developing the DiskANN Rust library. I am also an active maintainer of the Big ANN Benchmarks competition framework, and I recently helped organize the 1st Workshop on Vector Databases at ICML 2025.

I am interested in designing parallel and concurrent algorithms for solving problems related to similarity search, information retrieval, and computing nearest neighbors, with a particular focus on similarity search in high dimensions. I am the primary author of the ParlayANN repository, a benchmark suite of high-dimensional nearest neighbor algorithms, which currently ranks within the top five entries on ANN Benchmarks as of October 2025.

I received my PhD from Carnegie Mellon University, where I was advised by Guy Blelloch and supported by an NSF GRFP Fellowship. In Summer 2022, I interned with Harsha Vardhan Simhadri at Microsoft Research Redmond. I received my undergraduate degree in mathematics from MIT in 2019.

Preprints

• Range Retrieval with Graph-Based Indices. Magdalen Dobson Manohar, Taekseung Kim, Guy E. Blelloch.
  

• In-Place Updates of a Graph Index for Streaming Approximate Nearest Neighbor Search. Haike Xu, Magdalen Dobson Manohar, Philip A. Bernstein, Badrish Chandramouli, Richard Wen, Harsha Vardhan Simhadri.
  

• Results of the Big ANN: NeurIPS'23 competition. Harsha Vardhan Simhadri, Martin Aumüller, Amir Ingber, Matthijs Douze, George Williams, Magdalen Dobson Manohar, Dmitry Baranchuk, Edo Liberty, Frank Liu, Benjamin Landrum, Mazin Karjikar, Laxman Dhulipala, Meng Chen, Yue Chen, Rui Ma, Kai Zhang, Yuzheng Cai, Jiayang Shi, Yizhuo Chen, Weiguo Zheng, Zihao Wan, Jie Yin, Ben Huang.
  To appear in NeurIPS 2025.

Published Papers

• Cost-Effective, Low Latency Vector Search with Azure Cosmos DB. Nitish Upreti, Harsha Vardhan Simhadri, Hari Sudan Sundar, Krishnan Sundaram, Samer Boshra, Balachandar Perumalswamy, Shivam Atri, Martin Chisholm, Revti Raman Singh, Greg Yang, Tamara Hass, Nitesh Dudhey, Subramanyam Pattipaka, Mark Hildebrand, Magdalen Manohar, Jack Moffitt, Haiyang Xu, Naren Datha, Suryansh Gupta, Ravishankar Krishnaswamy, Prashant Gupta, Abhishek Sahu, Hemeswari Varada, Sudhanshu Barthwal, Ritika Mor, James Codella, Shaun Cooper, Kevin Pilch, Simon Moreno, Aayush Kataria, Santosh Kulkarni, Neil Deshpande, Amar Sagare, Dinesh Billa, Zishan Fu, Vipul Vishal.
  Proceedings of the VLDB Endowment, Volume 18.

• CLEANN: Lock-Free Augmented Trees for Low-Dimensional κ-Nearest Neighbor Search. Magdalen Dobson Manohar, Yuanhao Wei, Guy E. Blelloch.
  Proceedings of the 37th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2025.

• The DiskANN library: Graph-Based Indices for Fast, Fresh and Filtered Vector Search. Ravishankar Krishnaswamy, Magdalen Dobson Manohar, Harsha Vardhan Simhadri.
  IEEE Data Engineering Bulletin, Volume 48.

• ParlayANN: Scalable and Deterministic Parallel Graph-Based Approximate Nearest Neighbor Search Algorithms. Magdalen Dobson Manohar, Zheqi Shen, Guy E. Blelloch, Laxman Dhulipala, Yan Gu, Harsha Vardhan Simhadri, and Yihan Sun.
  Proceedings of the ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPoPP 2024.

• The Geometry of Tree-Based Sorting. Guy E. Blelloch and Magdalen Dobson.
  EATCS International Colloquium on Automata, Languages and Programming, ICALP 2023.

• Parallel Nearest Neighbors in Low Dimensions with Batch Updates. Guy E. Blelloch and Magdalen Dobson.
  Proceedings of the Symposium on Algorithm Engineering and Experiments, ALENEX 2022.

• Poster: The Problem-Based Benchmark Suite, V2. Daniel Anderson, Guy E. Blelloch, Laxman Dhulipala, Magdalen Dobson, and Yihan Sun.
  Proceedings of the ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming, PPoPP 2022.

• Multiagent Evaluation Mechanisms. Tal Alon, Magdalen Dobson, Ariel D. Procaccia, Inbal Talgam-Cohen, and Jamie Tucker-Folz.
  Proceedings of the AAAI Conference on Artificial Intelligence, AAAI 2020.

Teaching

• 15-451 Design and Analysis of Algorithms, Fall 2023
• 15-455 Undergraduate Complexity Theory, Spring 2022