jESevol

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jESevol
Pietro Terna
pietro.terna_at_unito.it   Department of
Economics and Finance G.Prato University of
Torino - Italy Evolving a simulated system of
enterprises with jESevol and Swarm
web.econ.unito.it/terna web.econ.unito.it/terna
/jes
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_jES-gtjESlet and jESevol
_______________________________________ jES
jESlet and jESevol _____________________________
__________
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jVE-gtjES
From jES
java Enterprise Simulator
to jESlet (with a didactic goal) and
to jESevol, to simulate an evolving
system of enterprises
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_overview
_______________________________________ Overview _
______________________________________
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overview 1
Overview 1/2 From jES (our java Enterprise
Simulator), we have derived jESevol, or
Evolutionary java Enterprise Simulator. jES is
a large Swarm-based package1 aimed at building
simulation models both of actual enterprises and
of virtual ones. jESevol simulates systems of
enterprises or production units in an
evolutionary context, where new ones arise
continuously and some of the old are dropped
out. Our environment is a social space with
metaphorical distances representing trustiness
and cooperation among production units (the
social capital). The production is represented by
a sequence of orders each order contains a
recipe, i.e. the description of the sequence of
activities to be done by several units to
complete a specific production. 1 Download
last versions of jES, jESlet and jESevol from
http//web.econ.unito.it/terna/jes
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overview 2
Overview 2/2 Two units can cooperate in the
production process only if they are mutually
visible in our social network. Units that do not
receive a sufficient quantity of orders, as well
as the ones that cannot send the accomplished
orders to successive units, disappear. New
enterprises arise, in the attempt of filling the
structural holes (Burt, 1992 Walker et al.,
1997) of our social network. A complex structure
emerges from our environment, with a difficult
and instable equilibrium whenever the social
capital is not sufficient. References Burt R.S.
(1992), Structural Holes The Social Structure
of Competition. Cambridge, MA, Harvard University
Press. Walker G., Kogut B., Shan W. (1997),
Social Capital, Structural Holes and the
Formation of an Industry Network, in Organization
Science. Vol. 8, No. 2, pp.109-25.
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evolving system
We look at an incomplete production system
continuously adapting itself to the reality
coming from the global demand of the market
while new firms arise and old ones are dropped
off To produce goods, supply chains are created
and modified, according to the changes in exiting
firms
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_jES basics
_______________________________________ jES
basics _______________________________________
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WD, DW, WDW
Three formalisms
WD side or formalism What to Do DW side or
formalism which is Doing What WDW formalism
When Doing What
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dictionary
A dictionary
unit a productive structure a unit is able to
perform one of the steps required to
accomplish an order order the object
representing a good to be produced an order
contains technical information (the recipe
describing the production steps) recipe a
sequence of steps to be executed to produce a
good
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_A flexible scheme
_______________________________________ A
flexible scheme in jESevol _______________________
________________
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DW a flexible scheme
DW
Units
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1
1
3
4
on a toroidal space
2
1
Each unit is able to do a specific step
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(left and right borders and top and bottom ones
are close together)
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WD recipes
WD
of a recipe
with the recipes of the orders (what to do)
expressed as sequences of numbers orders with
recipes are randomly generated with different
lengths and structures 1 3 2 4 5 3 4 3 5 1 1
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moving recipes
DW and WD
moving around among units
2
1
1 3 2 4
1
3
1 3 2 4
4
2
1 3 2 4
how to choose
1
?
1 3 2 4
5
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lack of visibility
Visibility is a metaphorical representation of
trustiness and cooperation in a social network
when global visibility increases, we have more
social capital
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visibility and
Visibility increases with the time (initial
visibility is randomly chosen)

• new units appear randomly (enterprise creation)
• with strategic relationships
• or alone

visibility changes
some units are dropped out
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bars
The left (blue) bar of each unit reports the
number of waiting orders (do be done)
The right (red) bar of each unit reports the
number of unsent products, due to the fact that a
unit able to do the required step does not exist
or is not visible
The down bar of each unit reports the number of
consecutive clock ticks in which the unit has
been idle
If gt maxInactivity the unit is dropped out and
all unsent products are lost
If gt maxUnsentProducts the unit is dropped out
and all unsent and waiting products are lost
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_an introductory case
_______________________________________ An
introductory case, robust and fragile ____________
___________________________
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the parameters, robust introductory case
Introductory robust case
potentialUnitTypes 5 unitGenerationInitialP
1 potentialUnitNumberPerType
2 newUnitGenerationP 0.0 interVisibilityMinLevel
0 increasingVisibilityStep 0.0 maxInactivity
10 maxUnsentProducts 10
max n. of types and max presence per type, here 5
2 with p1
p of a new unit in each cycle, with a random type
in this basic case all units are visible and
visibility does not change
we assume that an actual firm is dropped out from
the market after three months of inactivity, so
10 ticks 3 months of history
Why 10? Our recipes have here maxStepNumber 5
and maxStepLength2 potentially, in 10 ticks,
each unit can receive an order, but only as a
limit case with this parameters the system can
be exposed to a complete crash
similarly
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introductory case robust case
Introductory robust case
only 5 units kept alive
1,000 ticks 25 years of actual time
PRODUCTION
global/potential
final/potential
final/global
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the parameters, fragile introductory case
Introductory fragile case
potentialUnitTypes 10 unitGenerationInitialP
1 potentialUnitNumberPerType
1 newUnitGenerationP 0.0 interVisibilityMinLevel
0 increasingVisibilityStep 0.0 maxInactivity
10 maxUnsentProducts 10
max n. of types and max presence per type, here
10 1 with p1
Our recipes have here maxStepNumber 10 and
maxStepLength 1
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introductory case fragile case
Basic fragile case
no units kept alive
150 ticks lt 4 years of actual time
PRODUCTION
global/potential
final/potential
final/global
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_a study case
__________________________________________________
A study case, with 3 versions (i) basic, (ii)
increasing social capital, (iii) with greater
financial intervention of the banking
system ___________________________________________
_______
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the parameters, basic study case
(i) basic study case, starter file 5 in jESevol
0.3.00
potentialUnitTypes 5 unitGenerationInitialP
0.8 potentialUnitNumberPerType
2 newUnitGenerationP 0.8 interVisibilityMinLevel
1 increasingVisibilityStep 5 maxInactivity
10 maxUnsentProducts 10
max n. of types and max presence per type, here 5
2 with p0.8
p of a new unit in each cycle, with a random type
in this study case, min visibility is 1, i.e. at
least one common patch visibility increases of
5 patches in each tick
Our recipes have here maxStepNumber 5 and
maxStepLength 2
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study case basic
(i) basic study case, starter file 5 in jESevol
0.3.00
a relevant variability in the number of units
(social costs), with the trace of a cycle
a medium performance in term of potential
production
1,000 ticks 25 years of actual time
PRODUCTION
global/potential
final/potential
final/global
some form of structure seems to emerge
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the parameters, increasing social capital study
case
(ii) Increasing social capital study case,
starter file 5.2 in jESevol 0.3.00
potentialUnitTypes 5 unitGenerationInitialP
0.8 potentialUnitNumberPerType
2 newUnitGenerationP 0.8 interVisibilityMinLevel
1 increasingVisibilityStep 10 maxInactivity
10 maxUnsentProducts 10
max n. of types and max presence per type, here 5
2 with p0.8
p of a new unit in each cycle, with a random type
in this study case, min visibility is 1, i.e. at
least one common patch visibility increases of
10 patches in each tick
Our recipes have here maxStepNumber 5 and
maxStepLength 2
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study case increasing social capital
(ii) Increasing social capital study case,
starter file 5.2 in jESevol 0.3.00
a relevant variability in the number of units
(social costs), but now with an evident cycle
a good (and increasing) performance in term of
potential production
1,000 ticks 25 years of actual time
PRODUCTION
global/potential
final/potential
final/global
evident structures emerge
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the parameters, bank system study case
(iii) Greater financial intervention of the
banking system study case, starter file 5.3 in
jESevol 0.3.00
potentialUnitTypes 5 unitGenerationInitialP
0.8 potentialUnitNumberPerType
2 newUnitGenerationP 0.8 interVisibilityMinLevel
1 increasingVisibilityStep 5 maxInactivity
15 maxUnsentProducts 10
in this study case, min visibility is 1, i.e. at
least one common patch visibility is increases
of 5 patches in each tick
we assume that an actual firm is dropped out from
the market after 15 ticks of inactivity, instead
of 10
Our recipes have here maxStepNumber 5 and
maxStepLength 2
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study case bank system study case
(iii) Greater financial intervention of the
banking system study case, starter file 5.3 in
jESevol 0.3.00
a less relevant variability in the number of
units (reduced social cost)s, always with an
evident cycle
a good performance in term of potential
production
1,000 ticks 25 years of actual time
PRODUCTION
global/potential
final/potential
final/global
evident structures emerge
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Stability perspectives
Stability Cases i, ii and iii are stable also
running them for 4,000 ticks (one century)!
Short term enhancements A lot of investigation is
necessary on cases (i), (ii) and (iii) modelling
explicitly the banking system, with the
concurrent effects of the cases of bankruptcy in
firms and banks Using a Genetic Algorithm tool to
choose units to be created at each tick and where
to place them the fitness will be generated by
jESevol itself, from different points of view
the whole economic system, a specific unit, a
cluster of units,
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address again
Let run case 5.2 or 5.3 at the question time!

pietro.terna_at_unito.it  
web.econ.unito.it/terna web.econ.unito.it/t
erna/jes