Technically, the whole surface vibrates at a high frequency, typically tens of thousand Hertz~\cite{amberg11}.
This frequency is way beyond the tactile sensitivity range.
However, it creates an air cushion between the surface and the finger, which makes the surface feel more slippery.
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This project has two orthogonal challenges.
First, the technology was new and developed by colleagues with expertise in electrical engineering.
Therefore we had to work with research prototypes, called Stimtac, that were evolving in parallel to our own studies.
This simple example shows the rigidity of algorithmic behavior.
All information about the problem must be known in advance, the computing process is precisely defined, and the output is specified by the inputs~\cite{knuth68}.
Wegner and Goldin describe interaction as a more general model in which the machine is connected to input streams, that provide unpredictable data~\cite{goldin08}.
+They discuss interaction between systems, but Beaudouin-Lafon explains how their concept also applies to HCI~\cite{mbl08}.
They model interaction with co-induction as in the example in Listing~\ref{lst:coinduction}.
This example defines a stream of numbers, which is a non-finite structure, and a function that returns another stream in which numbers from the input stream are multiplied by \num{2}.
The co-inductive definition of the stream only has one constructor, identical to the second constructor of lists.
projects / hdr.git / commitdiff