Michael Chaly

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Michael Chaly, known online as Vizvezdenec, is a prominent contributor to the Stockfish development community. Born and currently residing in Sevastopol, he has made significant contributions to the Stockfish development community. Demonstrating exceptional mathematical skills, he secured third place in the Ukrainian School Math Olympics in 2004 and 2005. Graduating at the age of 15, he pursued higher education at Moscow Institute of Physics and Technology and St. Petersburg State University before completing his studies at Moscow State University in 2013, specializing in engineering mathematics and physics. His impactful contributions continue to shape the field of Stockfish development.


Michael Chaly’s journey into the intricacies of the game began with casual matches against a co-worker, whose level of expertise closely mirrored his own. This initial engagement sparked his curiosity about the competitive chess scene, prompting him to delve deeper into the world of professional chess. Inspired by a colleague’s admiration for Magnus Carlsen, Chaly’s interest was further kindled, leading him to explore the evolving landscape of the sport.


As an avid follower of top-tier competitions spanning various disciplines, Chaly’s exploration eventually led him to the Top Chess Engine Championship (TCEC). During his observation of these matches, he was enthralled by the strategic brilliance exhibited by an engine named Stockfish. What caught his attention was not only Stockfish’s aggressive gameplay but also the fact that it operated on an open-source framework, allowing enthusiasts like Chaly to delve into its underlying mechanics.

Motivated by this newfound passion, Chaly embarked on a mission to contribute to the enhancement of Stockfish. With the valuable support from Andrew Grant, author of Ethereal, he successfully established a robust system for crafting and implementing patches for Stockfish. This significant achievement took shape in late 2018, marking a milestone in Chaly’s journey as a chess enthusiast and contributor to the chess engine community.

Chaly’s impact in the realm of chess engines lies in his dedication to refining existing ideas within the domain of chess engine development. While he may not be the originator of groundbreaking concepts, his contributions have focused on the continuous improvement of chess engines. These enhancements span a range of aspects, from evaluating positions to optimizing search algorithms. Through his dedication and commitment, Chaly continues to play a vital role in the evolution of chess engines, shaping the future of this intellectually stimulating discipline.

Stockfish development

Michael Chaly main contributions to Stockfish:

  • Qsearch pruning techniques
    • Quiet evasions movecount pruning
    • 3rd futility pruning in Quiescence search
  • History pruning
  • Excluding double pawn protected squares from king ring for handcrafted evaluation (giving extra bonus as a defender for having f2 and h2 pawns in place)
  • Boosting up fianchetto defences etc
  • IIR for expected cutnodes
  • Allow captures in Late Move Reductions
  • Blending histories in Reverse Futility Pruning
  • Adjusting full depth search after Late Move Reductions
  • Negative Extensions after singular search
  • Post-LMR deeper searches
  • Pioneer of hyperscaling tunings (ie tuning values at extremely long time controls, with results ranging from -10 elo at 10s + 0.1s increment to 10 elo at 180 + 1.8s increment)