Denis Sokolov
Denis Sokolov

Applied research

Projects

01

Market design · Structural modeling

Parcoursup: Stable Choice with Overlapping Constraints

Estimated applicant preferences and compared the current fixed call-order mechanism (PCS) with Stage-Fair College-Proposing Deferred Acceptance (SF-CDA).

  • Modeled 886K applicants and 21K programs with a multinomial-logit preference model.
  • Benchmarked mechanisms with 1,000 full-market counterfactual simulations.
  • Improved scholarship-target compliance by 19.6 percentage points without reducing enrollment or completion speed.
SQLPandasStatsmodelsSimulation
02

Data pooling · Economic incentives

Marketplace ML & Online Advertising

Connected predictive accuracy to consumer reach, advertiser value, retailer-level lift, and participation incentives.

  • Complementary datasets increased total consumer capture and each retailer’s capture by 50%.
  • With asymmetric data ownership, pooling increased the smaller retailer’s audience by 200% while total capture stayed unchanged.
Ridge regressionCounterfactual analysisMarketplace ML
03

Machine learning · Certified removal

Efficient Newton Unlearning

Co-developed a scalable second-order method that removes selected data owners’ influence without full retraining.

  • Reused a global Hessian across unlearning requests, reducing per-client computation to O(d²).
  • Benchmarked non-IID logistic-regression workloads with up to 512 clients and 500 features.
  • Achieved lower parameter error than gradient ascent and faster runtime than standard Newton unlearning.
PythonNumPySciPyCertified removal
04

Matching theory · Algorithms

Resource-Regional Caps

Designed polynomial-time mechanisms for two-sided matching with shared regional resources and formal guarantees.

  • Designed six mechanisms with stability, fairness, efficiency, and incentive guarantees.
  • Evaluated 100 simulated markets with 100 students and 10 colleges.
  • A specialized mechanism eliminated conflicts when institutions had aligned priorities.
Matching theoryAlgorithm designPython simulation