http://www.santafe.edu/projects/swarm Varela et al. (1974) uses the term ``component'' rather than ``particle''; I prefer the latter term, because at any given time these entities may or may not be ``components'' of a higher level (autopoietic?) structure. Calling them ``components'' seems to me to obscure or prejudge this issue of the formation of higher level structures.  Formally, ``holes'' could be equally regarded as another ``element''; in which case we would say that every lattice position is always occupied by exactly one particle.  Again, formally, particle movement might be regarded as a special degenerate kind of ``reaction'', in which all reactants are conserved.  It might have been preferable to term links ``monomers''.  This is a particularly counter-intuitive, or unnatural aspect of this model; I speculate that this limitation was stipulated primarily in order to simplify the computer realisation of the model.  That is, it seems that 1.31 and 1.32 are not to be interpreted as a sequential refinements of 1.3, but rather as concurrent qualifications or constraints on it.  I conjecture that part of the explanation of this, and some other related peculiarities of the algorithm, may be that the algorithm was actually derived from a functional implementation (and thus inherited artifacts from it), rather than the algorithm having been written first and used as the specification of the implementation. However, this is of only historical interest at most.  Only three directions arise here, since one direction is already accounted for by the free L particle we are attempting to move at the higher level of the algorithm.  Steps 1.2 and 1.3, or 2.2 and 2.3, or 3.2 and 3.3.  Note that, with the specified initial condition of the space-holding only K and S particles, then, by conservation rules, there would always be guaranteed to be a hole available somewhere in the space, given that an L is being disintegrated; but if that initial constraint were relaxed, it would be possible that a hole might not be available at all.  Indeed, since the algorithm makes no stipulations at all about how this is to be done, locality could be completely ignored-for example by saying that the extra S particle should be put in a hole simply chosen uniformly from all holes in the space, without any regard to proximity to the disintegration site.  Note that L and K particle movements come before production in the algorithm; so produced L particles cannot separate from the K particle within a single iteration of the algorithm.  There is one L initially produced by EXP29.FOR that is still processed for bonding; but it is isolated from the other L particles and thus cannot bond in practise within that first timestep. In any case, that particular L particle does not appear in figure 5, indicating either an error in redrawing, or some detailed discrepancy between the code of EXP29.FOR and that actually used to generate this diagram.  Milan Zeleny, personal communication.  http://www.santafe.edu/projects/swarm  http://cbl.leeds.ac.uk/nikos/tex2html/doc/latex2html/latex2html.html  http://cbl.leeds.ac.uk/nikos/personal.html  http://www.arch.su.edu.au/ peterw/latex/harvard/  http://www.arch.su.edu.au/ peterw/index.html  I am indebted to Ms. Marita Prandoni of the Santa Fe Institute for her assistance in making this translation.  This is also available as a standalone source code file-see the Retrieval section.  [Escritura] NOTA: En esta busqueda no cuenta las veces en que encuentra elementos M en las fases + & * en la neuva ubicatión. Esto sultimo lo hace moverse preferentemente a lo largo de canales de M.  [Handwritten] Note: In this search, the times when an M particle in the + or * state is encountered in the new location are not counted. In this way there will be preferential movement along channels [?] of M.
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Timestamp: Tue Dec 31 18:43:32 GMT 1996