  Logical and information aspects of friction and wetting (including the
adhesion, capillarity, and superhydrophobicity) are discussed. Friction
involves paradoxes, such as the Painlev\'e paradoxes of non-existence or
non-uniqueness of solutions in mechanical systems of rigid bodies with dry
friction. These paradoxes can be treated by introducing ternary logic with the
three basic states: rest-motion-undefined. When elastic deformation is
introduced, the paradoxical solutions correspond to frictional instabilities
leading to rest-motion-unstable as three states of a system. The dynamic
evolution of a frictional interface towards a limit cycle can be viewed as a
process of erasing the information about the interface due to the
instabilities. Furthermore, while friction force is universal, it is not
treated as a fundamental force and can be considered as an epiphenomenon of
various synergetic mechanisms. This further relates friction to other surface
effects, including the capillarity, with its binary logic of wetting states and
a possibility of droplet computation for lab-on-a-chip microfluidic reactors.
We discuss the logical foundation of biomimetic superhydrophobic surface design
and how it is different from the conventional design. Both friction and wetting
can be used for novel unconventional logical and computational devices.
