For example, it is not necessary to pass through a stage as unstable as the 2-hole ladder (below) in growing a cube.
2-hole ladder: an unstable stage in previous growth sequence of a cube. |
By attempting to alternate polarity in insertions, we get this alternate growth sequence for a cube, which still has 8 stages:
Growth code:/n/.us/.ns/...uss
Growth sequence:
np (3-strut)
nudp (2-prism)
nupd (tetrahedron)
nnpupd (eared tetrahedron)
nnuppd (3-prism)
nnuudppd (camp chair)
nnuupdpd (boat dual)
nnuuppdd (cube)
The same strategy applied to the dodecahedron gives a growth sequence of the same number of stages (29) that successfully alternates insertion polarity all the way through.
/u/1ns/3us/2nss/5uss/3nsss/7uss/5nsss/9uss/7nsss
ud
unpd
undp
undudp
undupd
unnpdupd
unndpupd
unnduppd
unnduudppd
unnduupdpd
unnduuppdd
unnnpduuppdd
unnndpuuppdd
unnndupuppdd
unnnduupppdd
unnnduuudpppdd
unnnduuupdppdd
unnnduuuppdpdd
unnndnpuuuppdpdd
unnndnupuuppdpdd
unnndnuupuppdpdd
unnndnuuupppdpdd
unnndnuuuudpppdpdd
unnndnuuuupdppdpdd
unnndnuuuuppdpdpdd
unnndnunpuuuppdpdpdd
unnndnunupuuppdpdpdd
unnndnunuupuppdpdpdd
unnndnunuuupppdpdpdd