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short range particle-particle force interaction. External [[force fields]], such as [[gravitation]], can be also introduced, as long as the inter-collision motion of each particle can be represented by a simple one-step calculation.
Using LSA for spherical particles of different sizes and/or for jamming in a non-commeasureable size container proved to be a useful technique for generating and studying micro-structures formed under conditions of a [[crystallographic defect]]<ref>{{cite journal|doi=10.1007/bf02183698|title=Patterns of broken symmetry in the impurity-perturbed rigid-disk crystal|journal=Journal of Statistical Physics|volume=78|issue=3–4|pages=1011–1026|year=1995|last1=Stillinger|first1=Frank H.|last2=Lubachevsky|first2=Boris D.|bibcode=1995JSP....78.1011S}}</ref> or a [[geometrical frustration]]<ref>{{cite journal|doi=10.1103/physreve.70.041604|pmid=15600418|title=Epitaxial frustration in deposited packings of rigid disks and spheres|journal=Physical Review E|volume=70|issue=4|pages=041604|year=2004|last1=Lubachevsky|first1=Boris D.|last2=Stillinger|first2=Frank H.|bibcode=2004PhRvE..70d1604L|arxiv=cond-mat/0405650}}</ref><ref>{{cite journal|last1=Lubachevsky|first1=Boris D.
Any deviation from the spherical (or circular in two dimensions) shape, even a simplest one, when spheres are replaced with ellipsoids (or ellipses in two dimensions),<ref>{{cite journal|doi=10.1103/physrevlett.92.255506|pmid=15245027|title=Unusually Dense Crystal Packings of Ellipsoids|journal=Physical Review Letters|volume=92|issue=25|pages=255506|year=2004|last1=Donev|first1=Aleksandar|last2=Stillinger|first2=Frank H.|last3=Chaikin|first3=P. M.|last4=Torquato|first4=Salvatore|bibcode=2004PhRvL..92y5506D|arxiv=cond-mat/0403286}}</ref> causes thus modified LSA to slow down substantially.
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== History ==
The LSA was a by-product of an attempt to find a fair measure of [[speedup]] in [[Parallel algorithm|parallel]] [[simulations]]. The [[Time Warp (algorithm)|Time Warp]] parallel simulation algorithm by David Jefferson was advanced as a method to simulate asynchronous spatial interactions of fighting units in combat models on a [[parallel computer]].<ref>F. Wieland, and D. Jefferson, Case studies in serial and parallel simulations, Proc. 1989 Int'l Conf. Parallel Processing, Vol.III, F. Ris, and M. Kogge, Eds., pp. 255-258.</ref> Colliding particles models<ref>P. Hontales, B. Beckman, et al., Performance of the colliding pucks simulation of the Time Warp operating systems, Proc. 1989 SCS Multiconference, Simulation Series, SCS, Vol. 21, No. 2, pp. 3-7.</ref> offered similar simulation tasks with spatial interactions of particles but clear of the details that are non-essential for exposing the simulation techniques. The [[speedup]] was presented as the ratio of the execution time on a [[uniprocessor]] over that on a [[multiprocessor]], when executing the same parallel Time Warp algorithm. Boris D. Lubachevsky noticed that such a speedup assessment might be faulty because executing a [[parallel algorithm]] for a task on a uniprocessor is not necessarily the fastest way to perform the task on such a machine. The LSA was created in an attempt to produce a faster uniprocessor simulation and hence to have a more fair assessment of the [[parallel speedup]]. Later on, a parallel simulation algorithm, different from the Time Warp, was also proposed, that, when run on a uniprocessor, reduces to the LSA.<ref>{{cite journal|last=Lubachevsky|first=B.D.
== References ==
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