John Langford

Career

Langford earned a double bachelor's degree in physics and computer science at the California Institute of Technology in 1997 and a PhD at Carnegie Mellon University in 2002. Langford's page lists later work at Yahoo!, the Toyota Technological Institute and IBM's Watson Research Center, and Langford is now at Microsoft Research.³

Research

Langford's research projects include Isomap, Captcha, learning reductions, cover trees and contextual bandit learning, and Langford is the principal developer of Vowpal Wabbit and primary author of the hunch.net weblog. Langford is among the six authors of the Phi-4-reasoning-vision-15B technical report, a compact multimodal reasoning model released by Microsoft in 2026.³²¹

Work and contributions

• Phi-4-reasoning-vision-15B Open weights

  Co-author of the Phi-4-reasoning-vision-15B technical report and of the Microsoft Research post on lessons from training the model.¹²

• Vowpal Wabbit Open-source code

  Principal developer of the Vowpal Wabbit machine learning system, according to Langford's Microsoft Research page.³

Timeline

1. 1997Earned a double bachelor's degree in physics and computer science at Caltech.³
2. 2002Received a PhD from Carnegie Mellon University.³
3. Mar 4, 2026Co-authored Microsoft Research's post on training Phi-4-reasoning-vision-15B.¹

Other documented roles

Roles the sources document that are not confirmed as current.

• Research roles after 2002 (past), Yahoo!, Toyota Technological Institute and IBM Watson Research Center³

Where they work

• Microsoft 75 people in the wiki

Related people

• Xu TanAlso at Microsoft
• James McCaffreyAlso at Microsoft
• Jianfeng GaoAlso at Microsoft
• Sébastien BubeckAlso at Microsoft
• Weizhu ChenAlso at Microsoft
• Kenneth StanleyReinforcement learning · Machine-learning theory
• Jeff CluneReinforcement learning · Machine-learning theory
• Geoffrey HintonMachine-learning theory
• Hassan ShapourianMultimodal models
• Razvan PascanuMachine-learning theory