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WHAT IS IT?

Simulation of a pack train trade at Tatopani, Nepal. By Ralph Abraham, 19 November, 2011. Dzos (looks like a cow here) carry roce from Pkhara (Nepal) to Tatopani, half way to Jomosom on the border of Musthan (Tibetan region). Yaks (look like a rabbit here) carry salt from Jomosom to Tatopani.

HOW IT WORKS

At Tatopani, Nepalese unload rice bags and Tibetans unload salt bags. Then Nepalese load salt and Tibetans load rice, and the pack trains reverse and go home. Some heavy bargaining took place in advance of beginning the trek to esbalish the exchange rate.

HOW TO USE IT

Click “setup” and then “go” to view one complete cycle of trade.

THINGS TO NOTICE

The view of Annapurna and Daulaghiri from Ghorapani is fabulous.

THINGS TO TRY

Trade your wrist watch for a bag of rice.

EXTENDING THE MODEL

The predator-prey systems at each end the trade route which produce the surplus goods to trade should be included in the model. Exchange rate should be a slider.

NETLOGO FEATURES

It would be nice to have dzo and yak turtle shapes facing each way.

RELATED MODELS

Wolves and sheep in the Models Library.

CREDITS AND REFERENCES

Look here:
http://www.ralph-abraham.org/courses/ross-sys-2011/models.html
Thanks as always to Uri Wilensky and his team.

CODE

;;; trek.nlogo, by ralph abraham, 19 nov 2011 in rev 5.0 RC4

globals [ feed ] ;;; fuel used while trekking

to setup
  ca
  crt 1 [ ;;; trial dzo
    set size 4
    set shape "cow"
    set color yellow
    set heading 90
    set xcor -10
  ]
  crt 1 [ ;;; trial yak
    set size 3
    set shape "rabbit"
    set color red
    set heading 270
    set xcor 10
  ]
  crt 1 [ ;;; trial salt bag
    set size 2
    set shape "circle"
    set color white
    set heading 270
    set xcor 10
    set ycor 2
  ]
  crt 1 [ ;;; trial rice bag
    set size 2
    set shape "square"
    set color green
    set heading 90
    set xcor -10
    set ycor 2
  ]
  set feed 20
end

to step
  ask turtle 0 [ fd 1 wait 0.5 ] ;;; trial movement, dzo
  ask turtle 3 [ fd 1 wait 0.5 ] ;;; trial movement, rice bag
  ask turtle 1 [ fd 1 wait -0.5 ] ;;; trial movement, yak
  ask turtle 2 [ fd 1 wait -0.5 ] ;;; trial movement, salt bag
  set feed ( feed - 1 ) ;;; eat rate of dzo or yak
  plot feed
end

to step-back
  ask turtle 0 [ fd -1 wait 0.5 ] ;;; trial movement
  ask turtle 3 [ fd 1 wait 0.5 ] ;;; trial movement, rice bag
  ask turtle 1 [ fd -1 wait -0.5 ] ;;; trial movement
  ask turtle 2 [ fd 1 wait -0.5 ] ;;; trial movement, salt bag
  set feed ( feed - 1 ) ;;; eat rate of dzo or yak
  plot feed
end

to go
  repeat 10 [ step ]
  repeat 10 [ step-back ]
end


;;; end of code