Stef Tijs (August 31, 1937 – June 13, 2023), or Stephanus Hendrikus Tjis was a Dutch mathematician and a game theory pioneer in the Netherlands. He contributed to most subfields in game theory and particularly in cooperative game theory, where he introduced the Tijs value (later known as the τ value) in 1981 as a solution to n-person games alternative to the Shapley value and others.
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