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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

pentominoes.

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