[next] [prev] [up] Date: Mon, 14 Jun 93 01:53:16 +0200
[next] [prev] [up] From: Dik T. Winter <Dik.Winter@cwi.nl >
~~~ ~~~ [up] Subject: Contents of CFF31

Last Friday I received issue #31 of Cubism For Fun. A short summary of
the contents:

1. Short articles by Jan de Geus and Frans de Vreugd about Cube Day 1992.
2. An article by Herbert Kociemba about a classification of pretty
patterns on the cube.
3. Reflections by Tom Verhoeff about puzzles and computers.
4. Announcement by Koos Verhoef and Tom Verhoeff of a contest *.
5. A short article by Jaques Haubrich about Rubik's Tangle and how to
position 24 parts in a cube like way (four on a side).
6. An article by Jan Verbakel about the creation of castles with solid
7. A short article by Trevor Wood on the pecking of octacubes.
8. A short article by Jaques Haubrich about a difficult packing problem.
9. An article by David Singmaster about a gathering in Atlanta in honor
of Martin Gardner. (Nearly the whole puzzling world appears to have
been there.)
10. A new contest by Anton Hanegraaf.
11. Announcement of the 13th Dutch cube day on August 22 in Amsterdam.
This day is next to the 13th International Puzzle Party.

* This is an interesting puzzle indeed. Consider the densest sphere
packing in 3D. This is the packing where you start with a lattice
of spheres based on a triangular lattice, and put on top of it another,
similar, lattice such that each sphere of the new layer fits in a hole
in the lower layer. Add more layers. Pick from that all possible
configurations of 4 connected spheres. There are 25 such
configurations. The puzzle is to create from these 25 pieces a
pyramid with a side of 8 spheres (which contains 120 spheres), with
a hole at the center that consists of a pyramid with a side of 4
spheres (remember those sums of triangular numbers!). It is not
known whether there is a solution. The authors tell how they have
a TRS-80 now running 5 years on this problem, using backtracking
techniques. Until now the first 6 pieces did not move. The could
fit 24 pieces already 521,010 times. The puzzle was first announced
at the previous Cube Day.

CFF is a newsletter published by the Nederlandse Kubus Club NKC (Dutch
Cubists Club). It appears a bit irregular, but a few times a year.
Yearly membership fee is now NLG 25.- (Dutch Guilders) which amounts to
approximately $ 15.-. Information:
Anton Hanegraaf
Heemskerkstraat 9
6662 AL Elst
The Netherlands
(sorry, there is no e-mail address).
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland
home: bovenover 215, 1025 jn amsterdam, nederland; e-mail: dik@cwi.nl

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