  We give an expression for the norm of the space constructed by Tsirelson. The
implicit equation satisfied by this norm is dual to the implicit equation for
the norm of the dual of Tsirelson space given by Figiel and Johnson. The
expression can be modified to give the norm of the dual of any mixed Tsirelson
space. In particular, our results can be adapted to give the norm for the dual
of Schlumprecht space.
