Travel Sketches

Household Income, Travel Behavior, Location and Accessibility: Sketches From Two Different Developing Contexts

This paper analyzes the differences in travel behavior and location characteristics across different income groups in two cities in very different parts of the world – Chile and China. Using recent household travel surveys, we compare vehicle ownership rates, mode choices, trip rates and purposes, and travel times and distances according to high, middle, and low income terciles in Chengdu and S...

Sketches for Design and Design of Sketches

Design consists of generating ideas and adapting them to users. Cognitive research can give insights into each of these processes. Here, we describe two projects involving sketches. Sketches are cognitive tools; they have many uses, among them: to promote inferences and new ideas; to organize and convey information. For the former, ambiguity is productive; for the latter, clarity is necessary. ...

Finitary Sketches

Finitary sketches, i.e., sketches with nite-limit and nite-colimit specii-cations, are proved to be as strong as geometric sketches, i.e., sketches with nite-limit and arbitrary colimit speciications. Categories sketchable by such sketches are fully characterized in the innnitary rst-order logic: they are axiomatizable by-coherent theories, i.e., basic theories using nite conjunctions, countabl...

Proof Sketches

Nested Sketches

Since the fundamental work of Lawvere in 1963 [7] it is common to understand a theory as category with additional structure, to understand a model of the theory as a functor preserving the additional structure, and to represent homomorphisms by natural transformations. The resulting model category becomes a suitable subcategory of a functor category. Many different classes of mathematical struc...