  Under the extension of Curry-Howard's correspondence to classical logic,
Gentzen's NK and LK systems can be seen as syntax-directed systems of simple
types respectively for Parigot's Lambda Mu Calculus and Curien-Herbelin's
Lambda Bar Mu Mu Tidle Calculus. We aim at showing their computational
equivalence. We define translations between these calculi. We prove simulation
theorems for an undirected evaluation as well as for call-by-name and
call-by-value evaluations.
