```

```

#### NAME

```       sipd - simulate the spatial iterated Prisoner's Dilemma

```

#### SYNOPSIS

```       sipd -help
or
sipd   [-width integer] [-height integer] [-steps integer]
[-rounds integer] [-seed integer] [-CC double] [-CD
double]  [-DC  double] [-DD double] [-Iallc double]
[-Itft  double]  [-Irand  double]  [-Ipav   double]
[-Ialld   double]  [-rcp  double]  [-noise  double]
[-mute  double]  [-stats]  [-inv]  [-mag   integer]
[-term string]

```

#### DESCRIPTION

```       The  spatial  iterated Prisoner's Dilemma is simulated and
plotted over time according to the  specified  parameters.
Each  cell in a grid plays a specific strategy against its
eight neighbors for several rounds.  At  the  end  of  the
last round, each cell copies the strategy of its most suc-
cesful neighbor, which is then  used  for  the  next  time
step.   Possible  strategies  include  'Always Cooperate,'
'Always Defect,'

```

#### OPTIONS

```       -width integer
Width of world.

-height integer
Height of world.

-steps integer
Number of steps to simulate.

-rounds integer
Number of rounds per step.

-seed integer
Random seed for initial state.

-CC double
Reward Payoff.

-CD double
Sucker Payoff.

-DC double
Temptation Payoff.

-DD double
Punish Payoff.

-Iallc double
Initial population of All-C.

-Itft double
Initial population of TFT.

-Irand double
Initial population of Random.

-Ipav double
Initial population of Pavlov.

-Ialld double
Initial population of All-D.

-rcp double
Probability of C for Random strategy.

-noise double
Probability of noise.

-mute double
Probability of mutation.

-stats Print statistics?

-inv   Invert all colors?

-mag integer
Magnification factor.

-term string
How to plot points.

```

#### PAYOFFS

```       The payoff matrix for the Prisoner's Dilemma game is  usu-
ally expressed as:
Player B's Move
+-----------+-----------+
Player A's Move | cooperate |  defect   |
+-----------+-----------+-----------+
| cooperate |  CC, CC   |  CD, DC   |
+-----------+-----------+-----------+
|    defect |  DC, CD   |  DD, DD   |
+-----------+-----------+-----------+

where  the  table entries are (A's payoff, B's payoff) and
CC, CD, DC, and DD are the reward, sucker, temptation, and
punish payoffs, respectively.  For each of these four out-
comes you will probably want the payoffs  to  reflect  the
relationships:

(DC > CC > DD > CD) and ((CD + DC) / 2 < CC).

```

#### MISCELLANY

```       The  option for the probability of mutation (-mute) corre-
sponds to the act of a cell spontaneously  changing  to  a

randomly  selected  strategy independent of the outcome of
the most recent set of rounds.

random noise (via the -noise option) manifests itself as a
cell  making  a  randomly selected move in a single round.
In this case, both the cell whose action  was  altered  as
well  as  that cell's opponents "remember" what the random
move was on the next round.

The value supplied with the -term option may be "none," in
which case no graphic output is performed.  This is useful
if you simply want the statistics  to  be  calculated  for
each time step (via the -stats option).

The  initial  population levels for all strategies will be
normalized, so the scaling of the option values is irrele-
vant.

```

#### BUGS

```       No  sanity  checks  are performed to make sure that any of
the options make sense.

```

#### AUTHOR

```       Copyright (c) 1997, Gary William Flake.

Permission granted for any use according to  the  standard
GNU ``copyleft'' agreement provided that the author's com-
ments are neither modified nor removed.   No  warranty  is
given or implied.

```

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