Wittgenstein on Free Monoids

[timelets]

11. ...Our language can be regarded as an ancient city: a maze of little streets and squares, of old and new houses, of houses with extensions from various periods, and all this surrounded by a multitude of new suburbs with straight and regular streets and uniform houses.

L.W. Phil. Inv. 4ed. p. 11

A street is an expression made of houses and navigation spaces.