[net.arch] topology

kevin@sun.uucp (Kevin Sheehan) (04/24/85)

<just a thought>

There has been a recent discussion regarding various orders of "hypercube"
topolgies in parallel computing.  One of the topics of conversation was the
influence of structure on communications (path lengths, node delay, etc.)

One of the things that struck me was the analysis of path in a "square"
structure.  I have seen a discussion of cube and various N-dimensional
equivalents, and the properties they posess.  My fuel to the fire would
be the addition of the property of simplest N-gon in the space as a model.

As example, consider this contrast between the construction of "square"
objects in a given space, and the simplest.

dimension 0
1 point			/1 point	 (obvious, but let's start simple)
dimension 1
2 points = line		/2 points = line
dimension 2
4 points, 4 lines = square	/3 points, three lines = triangle
dimension 3
8 pts, 6 faces,12 lines = cube	/4 pts, 4 triangles, 6 lines = tetrahedron
dimension 4
16 pts, ... 8 cubes hypercube tesseract /5 pts ... 5 tetra's = polytetrahedron

the mind boggles after that.

Anyway, the simpler system seems to have the propery of being completely
connected.  ie, in a cube to get from one corner to the opposite, you
have either 2 (same plane) or three (other corner) paths to cross.

In a tetrahedron, all vertices (nodes) are directly connected.  Now the
match - what impact would this have on current topolgies suggested for
the "hypercube" computers, and what impact on other things based on
pure right angle reasoning?

			l & h,
			kev

PS or the Zen alternative, am I full of *? - if replies are anatomical
in nature, please be specific :-)