Grounding at a distance

Computation at a Distance

We consider a model of computation motivated by possible limitations on quantum computers. We have a linear array of n wires, and we may perform operations only on pairs of adjacent wires. Our goal is to build a circuits that perform specified operations spanning all n wires. We show that the natural lower bound of n− 1 on circuit depth is nearly tight for a variety of problems, and we prove li...

Design at a distance

The Open University has been teaching design at a distance for three decades. In this time delivery mechanisms have changed from non-interactive broadcasts to interactive media. A new generation of courses is emerging taught entirely online. This offers many challenges and opportunities This paper describes three tools that will be used in a new, level 1 course. Knowledge mapping, animated scre...

Comparison at a distance.

The visual system is known to contain hard-wired mechanisms that compare the values of a given stimulus attribute at adjacent positions in the visual field; but how are comparisons performed when the stimuli are not adjacent? We ask empirically how well a human observer can compare two stimuli that are separated in the visual field. For the stimulus attributes of spatial frequency, contrast, an...

Symbol Grounding: A New Look At An Old Idea

Proteins: interaction at a distance

How do the surface side chains of a protein behave when it binds to another protein? Do they optimize interactions by crumpling inwards or by extending outwards?