  The application to main-sequence stars of the rotation-induced mixing theory
in the presence of mu-gradients leads to partial mixing in the lithium
destruction region, not visible in the atmosphere. The induced lithium
depletion becomes visible in the sub-giant phase as soon as the convective zone
deepens enough. This may explain why the observed " lithium dilution " is
smoother and the final dilution factor larger than obtained in standard models,
while the lithium abundance variations are very small on the main sequence.
