small worlds (alan roach, carlos gershenson, joana simoes, daniel knabe, konrad diwold ) |
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To explore the dynamics of small world networks we focussed on modelling sex networks and
the spreading of sexually transmitted diseases (stds)
using Starlogo, Visual Basic and Mathematica. To give rise to a small world network it was
assumed that agents who already had a lot of different sex partners are more attractive and
will therfor be chosen
as a partner with a higher probability. Each agent was equipped with a list of previous
encounters which also allowed to reconstruct the network.
When infected, an agent would die, and therfor be removed from the population
after a predefined lethal period. The spreading of diseases depended on latency period,
lethal period and most of all on the structure of the network.
In small world networks diseases were almost bound to extinct a popuplation once they
managed to infect highly promiscous people, which served as network hubs.
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| download: |
small-world.vb.zip ( 24 kb, visual basic required) |
spatial agents (andres pegam, carsten wittenberg, udo wächter) |
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The german psychologist Bischof has developed a cybernetic model of agents to simulate how they move around in space,
in relation to other agents. The model is built on empirical data that has been selected both in psychology and behavioural studies over the last few decades.
The aim of the project at AMHSO was to develop a client-server framework based on java, to implement a spatial agents simulation.
The agents might be visualized as balls in space that are interconnected by strings, and could not only be used for modelling
agent behaviour but also as a psychologically motivated clustering method for highdimensional data.
The basic architecture was implemented during the workshop and is still being further developed by the group.
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| link: |
intro to the bischoff modell (German only) |
sleeping patterns (carlo comis, martin schneider) |
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Using netlogo - a powerful successor to starlogo - it was shown how activity patterns
can emerge in a prey/predator world with a day/night cycle.
Starting out with a simple grass-sheep-wolves simulation, wolves and sheep were equipped with an internal clock,
that had a fixed circadian period, and the ability to synchronize with the daylight cycle using
light as a zeitgeber mechanism. Each time the zeitgeber was triggered the phasis of the internal clock
was offset by a predefined amount. All these parameters were subject to darwinian evolution,
so that we expected temporal niching to occur. The effective outcome would depend very much on wether prey are
harder or easier to catch when they are asleep (both options occuring in nature). If observable
niching occured at all was very much dependent on the evolutionary parameters and the relative
time scale of reproduction rate and daylight cycle.
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| download: |
sleeping-patterns.logo (17 kb, early version) |
turtles in love (meike aulbach, miriam kreyenborg) |
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The group started out using Sternbers triangular model of love and developed a visualisation for
various kinds of love which involve passion, comitment and intimacy in varying degrees.
Since Sternbergs theory is rather a theory of relationships, additional parameters were needed
to model if agents fall in love in the first place. With the help of Erich Fromms 'Kunst des Liebens' these factors were devided into material, intellectual, physical and social love-parameters.
As a third influence a psychological factor was introduced that should reflect 'random' behaviour that cannot be captured by the modell.
Wether a couple would fall in love and how long it would stick together is then determined by the love formula that
considers all of the above parameters.
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| download: |
turtles-in-love.pdf (160 kb) |
turtles-in-love.slogo (40 kb)
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pattern formation (abdiel caceres) |
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A cellular automaton based on a chemical activator-inhibitor model was developed in starlogo
to simulate the development of zebra patterns.
One of the chemicals triggerd either white or black hair depending on
its concentration.
The model produced stripes similar to those of zebras but it deviated from
real zebra patterns in various respects:
Original zebra patterns showcase mirror symmetry along the spinal chord as well as high pattern stability during
growth. It was suggested that using voroni-like cells on a continuous plane rather than
a fixed rectangular lattice may improve the results.
To obtain symmetry one might also model cellular development,
by running the chemical process on a cellular automaton that grows according to embriological rules.
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structures in rule110 (genaro martinez) |
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Using Osxlcau, a tool for investigating cellular automata dynamics,
a number of novelties for the rule110 CA, including a glider eater were discovered.
So far several collisions of pairs of gliders have been shown to produce new gliders.
These collisions have been used to emulate a cyclic tag system, thus showing the universality of rule 110.
In Conways game of live universality had been proven, using gliders and glider eaters emulating
a von Neuman computer with logical operators.
During the AMHSO workshop a triple glider collison was discovered that results in the deletion
of two of the gliders whereas the third glider survives.
The third glider may therfor be referred to as glider eater, with respect to this situation.
The discovery of such structures may give rise to an alternative approch of proving universality in rule 110.
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| download: |
rule110-eat.gif | gliderb-3.gif | rule110-shift.gif |
sperm rules (andrei kouznetsov) |
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The dynamics of sperm mediated gene transfer were simulated using Starlogo.
The basic ingredients were stationary ova represented by patches
and mobile sperm cells represented by turtles.
Whenever a sperm cell ran into an ova they would merge their genes using crossover and mutation,
and the modified sperm cell would then continue its journey.
The genome was a simple real number, with crossover corresponding to the mean value and
mutation to adding a constant. Thus the gene could easily be visualized using the
Starlogo color space. Since this colorspace is wrapped around, it provides a modulo effect,
which causes complex nonlinear behaviour as seen in multiply recursive functions.
The discontinuity caused by the modulo effect corresponds nicely with discontinuities observed in real world genetic processes.
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| download: |
sperm-rules.pdf (794 kb) | sperm-toy.pdf (35 kb) | sperm-toy.slogo (26 kb) |
