Jean-Louis Verdier (French: [v??dje]; 2 February 1935 – 25 August 1989) was a French mathematician who worked, under the guidance of Alexander Grothendieck, on derived categories and Verdier duality.
Verdier called the condition (w) for Whitney, as at the time he thought (w) might be equivalent to Whitney's condition (b).
Real algebraic examples for which the Whitney conditions hold but Verdier's condition (w) fails, were constructed by David Trotman who has obtained many geometric properties of (w)-regular stratifications.
Work of Bernard Teissier, aided by Jean-Pierre Henry and Michel Merle at the École Polytechnique, led to the 1982 result that Verdier's condition (w) is equivalent to the Whitney conditions for complex analytic stratifications.
Verdier later worked on the theory of integrable systems.