Formal Representations and Informal Presentations

We now turn to the transition from pictures composed of and including graphical symbols to more complex pictorial presentations, whose meaning can no longer be captured easily by Fregean structures. This immediately raises the issue of formalization: To what extent can or even should information encoded in pictures be represented formally, and how can the informal context, which traditionally has been handled implicitly in humancomputer interaction, be treated algorithmically and conveyed to users?