globals [ counter i ;;number of turtles with each strategy num-random num-cooperate num-defect num-tit-for-tat num-unforgiving num-unknown num-tit-for-two-tats num-tit-for-three-tats num-two-tits-for-tat num-three-tits-for-tat num-majority ;;number of interactions by each strategy num-random-games num-cooperate-games num-defect-games num-tit-for-tat-games num-unforgiving-games num-unknown-games num-tit-for-two-tats-games num-tit-for-three-tats-games num-two-tits-for-tat-games num-three-tits-for-tat-games num-majority-games ;;total score of all turtles playing each strategy random-score cooperate-score defect-score tit-for-tat-score unforgiving-score unknown-score tit-for-two-tats-score tit-for-three-tats-score two-tits-for-tat-score three-tits-for-tat-score majority-score ;;total number of turtles number-of-turtles ;;average scores random-avg-score cooperate-avg-score defect-avg-score tit-for-tat-avg-score unforgiving-avg-score unknown-avg-score tit-for-two-tats-avg-score tit-for-three-tats-avg-score two-tits-for-tat-avg-score three-tits-for-tat-avg-score majority-avg-score ;; number of to-be-kids ;;number of turtles with each strategy numkids-random numkids-cooperate numkids-defect numkids-tit-for-tat numkids-unforgiving numkids-unknown numkids-tit-for-two-tats numkids-tit-for-three-tats numkids-two-tits-for-tat numkids-three-tits-for-tat numkids-majority ] turtles-own [ score strategy defect-now? partner-defected? ;;action of the partner partner-defected1? ;;did my partner defect two rounds ago? partner-defected2?;;did my partner defect three rounds ago? partner-defected3?;;did my partner defect four rounds ago? partnered? ;;am I partnered? partner ;;WHO of my partner (nobody if not partnered) partner-history ;;a list containing information about past interactions ;;with other turtles (indexed by WHO values) partner-history1 ;;a list containing information about past interactions ;;with other turtles (indexed by WHO values) partner-history2 ;;a list containing information about past interactions ;;with other turtles (indexed by WHO values) partner-history3 ;;a list containing information about past interactions ;;with other turtles (indexed by WHO values) pastones ;;list with a list of n previous interactions. ] ;;;;;;;;;;;;;;;;;;;;;; ;;;Setup Procedures;;; ;;;;;;;;;;;;;;;;;;;;;; to setup clear-turtles ;; Do not clear all, because population plot mustnt be cleared every turn. set-current-plot "Average Payoff" clear-plot clear-drawing clear-patches reset-scores reset-games store-initial-turtle-counts ;;record the number of turtles created for each strategy setup-turtles ;;setup the turtles and distribute them randomly end ;;record the number of turtles created for each strategy ;;The number of turtles of each strategy is used when calculating average payoffs. ;;Slider values might change over time, so we need to record their settings. ;;Counting the turtles would also work, but slows the model. to store-initial-turtle-counts set num-random n-random set num-cooperate n-cooperate set num-defect n-defect set num-tit-for-tat n-tit-for-tat set num-unforgiving n-unforgiving set num-unknown n-unknown set num-tit-for-two-tats n-tit-for-two-tats set num-tit-for-three-tats n-tit-for-three-tats set num-two-tits-for-tat n-two-tits-for-tat set num-three-tits-for-tat n-three-tits-for-tat set num-majority n-majority end ;;setup the turtles and distribute them randomly to setup-turtles make-turtles ;;create the appropriate number of turtles playing each strategy setup-common-variables ;;sets the variables that all turtles share end ;;create the appropriate number of turtles playing each strategy to make-turtles crt num-random [ set strategy "random" set color gray - 1 ] crt num-cooperate [ set strategy "cooperate" set color red ] crt num-defect [ set strategy "defect" set color blue ] crt num-tit-for-tat [ set strategy "tit-for-tat" set color lime ] crt num-unforgiving [ set strategy "unforgiving" set color turquoise - 1 ] crt num-unknown [set strategy "unknown" set color magenta ] crt num-tit-for-two-tats [set strategy "tit-for-two-tats" set color violet] crt num-tit-for-three-tats [set strategy "tit-for-three-tats" set color orange ] crt num-two-tits-for-tat [set strategy "two-tits-for-tat" set color green ] crt num-three-tits-for-tat [set strategy "three-tits-for-tat" set color brown ] crt num-majority [set strategy "majority" set color yellow ] end ;;set the variables that all turtles share to setup-common-variables ask turtles [ set score 0 set partnered? false set partner nobody setxy random-xcor random-ycor ] setup-history-lists ;;initialize PARTNER-HISTORY list in all turtles end ;;initialize PARTNER-HISTORY list in all turtles to setup-history-lists let num-turtles count turtles let default-history [] ;;initialize the DEFAULT-HISTORY variable to be a list let default-history1 [] ;;initialize the DEFAULT-HISTORY variable to be a list let default-history2 [] ;;initialize the DEFAULT-HISTORY variable to be a list let default-history3 [] ;;initialize the DEFAULT-HISTORY variable to be a list ;;create a list with NUM-TURTLE elements for storing partner histories repeat num-turtles [ set default-history (fput false default-history) ] ;;give each turtle a copy of this list for tracking partner histories ask turtles [ set partner-history default-history ] ;;same thing for older actions ;;create a list with NUM-TURTLE elements for storing partner histories repeat num-turtles [ set default-history1 (fput false default-history1) ] ;;give each turtle a copy of this list for tracking partner histories ask turtles [ set partner-history1 default-history1 ] ;;create a list with NUM-TURTLE elements for storing partner histories repeat num-turtles [ set default-history2 (fput false default-history2) ] ;;give each turtle a copy of this list for tracking partner histories ask turtles [ set partner-history2 default-history2 ] ;;create a list with NUM-TURTLE elements for storing partner histories repeat num-turtles [ set default-history3 (fput false default-history3) ] ;;give each turtle a copy of this list for tracking partner histories ask turtles [ set partner-history3 default-history3 ] end ;;;;;;;;;;;;;;;;;;;;;;;; ;;;Runtime Procedures;;; ;;;;;;;;;;;;;;;;;;;;;;;; ;; This is for simulation with changing populations. to do-popdyn clear-last-round if counter >= maxcounter [ set counter 0 do-avg-score count-to-be-kids print num-tit-for-tat-games do-popplot set-new-n setup ] ask turtles [ partner-up ] ;;have turtles try to find a partner let partnered-turtles turtles with [ partnered? ] ask partnered-turtles [ select-action ] ;;all partnered turtles select action ask partnered-turtles [ play-a-round ] do-bookkeeping set counter counter + 1 display ;; Updates the screen end ;; This is for simulation with fixed population sizes. to go clear-last-round if counter >= maxcounter [ set counter 0 do-popplot printscore stop ] ask turtles [ partner-up ] ;;have turtles try to find a partner let partnered-turtles turtles with [ partnered? ] ask partnered-turtles [ select-action ] ;;all partnered turtles select action ask partnered-turtles [ play-a-round ] do-bookkeeping set counter counter + 1 display ;; Updates the screen end to clear-last-round let partnered-turtles turtles with [ partnered? ] ask partnered-turtles [ release-partners ] end ;;release partner and turn around to leave to release-partners set partnered? false set partner nobody rt 180 set label "" end ;;have turtles try to find a partner ;;Since other turtles that have already executed partner-up may have ;;caused the turtle executing partner-up to be partnered, ;;a check is needed to make sure the calling turtle isn't partnered. to partner-up ;;turtle procedure if (not partnered?) [ ;;make sure still not partnered rt (random-float 90 - random-float 90) fd 1 ;;move around randomly set partner one-of (turtles-at -1 0) with [ not partnered? ] if partner = self [set partner nobody] if partner != nobody [ ;;if successful grabbing a partner, partner up set partnered? true set heading 270 ;;face partner ask partner [ set partnered? true set partner myself set heading 90 ] ] ] end ;;choose an action based upon the strategy being played to select-action ;;turtle procedure if (strategy = "random") [ act-randomly ] if (strategy = "cooperate") [ cooperate ] if (strategy = "defect") [ defect ] if (strategy = "tit-for-tat") [ tit-for-tat ] if (strategy = "unknown") [ unknown ] if (strategy = "tit-for-two-tats") [ tit-for-two-tats ] if (strategy = "tit-for-three-tats") [ tit-for-three-tats ] if (strategy = "two-tits-for-tat") [ two-tits-for-tat ] if (strategy = "three-tits-for-tat") [ three-tits-for-tat ] if (strategy = "unforgiving") [ unforgiving ] if (strategy = "majority") [ majority ] end to play-a-round ;;turtle procedure get-payoff ;;calculate the payoff for this round update-history ;;store the results for next time end ;;calculate the payoff for this round and ;;display a label with that payoff. to get-payoff set partner-defected? [defect-now?] of partner ifelse partner-defected? [ ifelse defect-now? [ set score (score + 1) set label 1 ] [ set score (score + 0) set label 0 ] ] [ ifelse defect-now? [ set score (score + 5) set label 5 ] [ set score (score + 3) set label 3 ] ] end ;;update PARTNER-HISTORY based upon the strategy being played to update-history if strategy = "random" [ act-randomly-history-update ] if strategy = "cooperate" [ cooperate-history-update ] if strategy = "defect" [ defect-history-update ] if strategy = "tit-for-tat" [ tit-for-tat-history-update ] if strategy = "unforgiving" [ unforgiving-history-update ] if (strategy = "unknown") [ unknown-history-update ] if (strategy = "tit-for-two-tats") [ tit-for-two-tats-history-update ] if (strategy = "tit-for-three-tats") [ tit-for-three-tats-history-update ] if (strategy = "two-tits-for-tat") [ two-tits-for-tat-history-update ] if (strategy = "three-tits-for-tat") [ three-tits-for-tat-history-update ] if (strategy = "majority") [ majority-history-update ] end ;;;;;;;;;;;;;;;; ;;;Strategies;;; ;;;;;;;;;;;;;;;; ;;All the strategies are described in the Information Tab. to act-randomly set num-random-games num-random-games + 1 ifelse (random-float 1.0 < 0.5) [ set defect-now? false ] [ set defect-now? true ] end to act-randomly-history-update ;;uses no history- this is just for similarity with the other strategies end to cooperate set num-cooperate-games num-cooperate-games + 1 ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] end to cooperate-history-update ;;uses no history- this is just for similarity with the other strategies end to defect set num-defect-games num-defect-games + 1 ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] end to defect-history-update ;;uses no history- this is just for similarity with the other strategies end to tit-for-tat set num-tit-for-tat-games num-tit-for-tat-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to tit-for-tat-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;; Note: Unforgiving never makes trembling hand mistakes. to unforgiving set num-unforgiving-games num-unforgiving-games + 1 set partner-defected? item ([who] of partner) partner-history ifelse (partner-defected?) [set defect-now? true] [set defect-now? false] end to unforgiving-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) end ;;defaults to tit-for-tat ;;can you do better? to unknown set num-unknown-games num-unknown-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end ;;defaults to tit-for-tat-history-update ;;can you do better? to unknown-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end to tit-for-two-tats set num-tit-for-two-tats-games num-tit-for-two-tats-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected? and partner-defected1? and partner-defected2?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to tit-for-two-tats-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;;tit-for-three-tats to tit-for-three-tats set num-tit-for-three-tats-games num-tit-for-three-tats-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected? and partner-defected1? and partner-defected2? and partner-defected3?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to tit-for-three-tats-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;;two-tits-for-tat to two-tits-for-tat set num-two-tits-for-tat-games num-two-tits-for-tat-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected? or partner-defected1? or partner-defected2?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to two-tits-for-tat-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;;three-tits-for-tat to three-tits-for-tat set num-three-tits-for-tat-games num-three-tits-for-tat-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse (partner-defected? or partner-defected1? or partner-defected2? or partner-defected3?) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to three-tits-for-tat-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;;majority to majority set num-majority-games num-majority-games + 1 set partner-defected? item ([who] of partner) partner-history set partner-defected1? item ([who] of partner) partner-history1 set partner-defected2? item ([who] of partner) partner-history2 set partner-defected3? item ([who] of partner) partner-history3 ifelse ((partner-defected? and partner-defected1?) or (partner-defected? and partner-defected2?) or (partner-defected1? and partner-defected2?)) [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? true ] [set defect-now? false ] ] [ ifelse (random 100 >= tremblinghand-prob) [set defect-now? false ] [set defect-now? true ] ] end to majority-history-update if (random 100 < mistakehearing-prob) [ifelse partner-defected? = true [set partner-defected? false] [set partner-defected? true] ] set partner-history (replace-item ([who] of partner) partner-history partner-defected?) set partner-history1 (replace-item ([who] of partner) partner-history1 partner-defected?) set partner-history2 (replace-item ([who] of partner) partner-history2 partner-defected1?) set partner-history3 (replace-item ([who] of partner) partner-history3 partner-defected2?) end ;;;;;;;;;;;;;;;;;;;;;;;;; ;;;Plotting Procedures;;; ;;;;;;;;;;;;;;;;;;;;;;;;; ;;procedure called by go that calculates scores and plots to do-bookkeeping do-scoring do-plotting end to reset-scores set random-score 0 set cooperate-score 0 set defect-score 0 set tit-for-tat-score 0 set unforgiving-score 0 set unknown-score 0 set tit-for-two-tats-score 0 set tit-for-three-tats-score 0 set two-tits-for-tat-score 0 set three-tits-for-tat-score 0 set majority-score 0 end to reset-games set num-random-games 0 set num-cooperate-games 0 set num-defect-games 0 set num-tit-for-tat-games 0 set num-unforgiving-games 0 set num-unknown-games 0 set num-tit-for-two-tats-games 0 set num-tit-for-three-tats-games 0 set num-two-tits-for-tat-games 0 set num-three-tits-for-tat-games 0 set num-majority-games 0 end ;;calculate the total scores of each strategy to do-scoring set random-score (calc-score "random" num-random) set cooperate-score (calc-score "cooperate" num-cooperate) set defect-score (calc-score "defect" num-defect) set tit-for-tat-score (calc-score "tit-for-tat" num-tit-for-tat) set unforgiving-score (calc-score "unforgiving" num-unforgiving) set unknown-score (calc-score "unknown" num-unknown) set tit-for-two-tats-score (calc-score "tit-for-two-tats" num-tit-for-two-tats) set tit-for-three-tats-score (calc-score "tit-for-three-tats" num-tit-for-three-tats) set two-tits-for-tat-score (calc-score "two-tits-for-tat" num-two-tits-for-tat) set three-tits-for-tat-score (calc-score "three-tits-for-tat" num-three-tits-for-tat) set majority-score (calc-score "majority" num-majority) end to do-avg-score ifelse num-random-games = 0 [set random-avg-score 0] [set random-avg-score random-score / (num-random-games)] ifelse num-cooperate-games = 0 [set cooperate-avg-score 0] [set cooperate-avg-score cooperate-score / (num-cooperate-games)] ifelse num-defect-games = 0 [set defect-avg-score 0] [set defect-avg-score defect-score / (num-defect-games)] ifelse num-tit-for-tat-games = 0 [set tit-for-tat-avg-score 0] [set tit-for-tat-avg-score tit-for-tat-score / (num-tit-for-tat-games)] ifelse num-unforgiving-games = 0 [set unforgiving-avg-score 0] [set unforgiving-avg-score unforgiving-score / (num-unforgiving-games)] ifelse num-unknown-games = 0 [set unknown-avg-score 0] [set unknown-avg-score unknown-score / (num-unknown-games)] ifelse num-tit-for-two-tats-games = 0 [set tit-for-two-tats-avg-score 0] [set tit-for-two-tats-avg-score tit-for-two-tats-score / (num-tit-for-two-tats-games)] ifelse num-tit-for-three-tats-games = 0 [set tit-for-three-tats-avg-score 0] [set tit-for-three-tats-avg-score tit-for-three-tats-score / (num-tit-for-three-tats-games)] ifelse num-two-tits-for-tat-games = 0 [set two-tits-for-tat-avg-score 0] [set two-tits-for-tat-avg-score two-tits-for-tat-score / (num-two-tits-for-tat-games)] ifelse num-three-tits-for-tat-games = 0 [set three-tits-for-tat-avg-score 0] [set three-tits-for-tat-avg-score three-tits-for-tat-score / (num-three-tits-for-tat-games)] ifelse num-majority-games = 0 [set majority-avg-score 0] [set majority-avg-score majority-score / (num-majority-games)] end to-report count-turtles set number-of-turtles count turtles report number-of-turtles end to-report sumpoints let sumpoint 0 do-avg-score set sumpoint sumpoint + random-avg-score + cooperate-avg-score + defect-avg-score + tit-for-tat-avg-score set sumpoint sumpoint + unforgiving-avg-score + unknown-avg-score + tit-for-two-tats-avg-score + tit-for-three-tats-avg-score set sumpoint sumpoint + two-tits-for-tat-avg-score + three-tits-for-tat-avg-score + majority-avg-score report sumpoint end to-report sumkids let sumkid 0 set sumkid sumkid + random-avg-score * num-random + cooperate-avg-score * num-cooperate set sumkid sumkid + defect-avg-score * num-defect + tit-for-tat-avg-score * num-tit-for-tat set sumkid sumkid + unforgiving-avg-score * num-unforgiving + unknown-avg-score * num-unknown set sumkid sumkid + tit-for-two-tats-avg-score * num-tit-for-two-tats + tit-for-three-tats-avg-score * num-tit-for-three-tats set sumkid sumkid + two-tits-for-tat-avg-score * num-two-tits-for-tat + three-tits-for-tat-avg-score * num-three-tits-for-tat set sumkid sumkid + majority-avg-score * num-majority report sumkid end ;; returns the total score for a strategy if any turtles exist that are playing it to-report calc-score [strategy-type num-with-strategy] ifelse num-with-strategy > 0 [ report (sum [ score ] of (turtles with [ strategy = strategy-type ])) ] [ report 0 ] end ;;if a strategy has had any interactions, plot the average score per interaction to do-plotting set-current-plot "Average Payoff" if num-random-games > 0 [ set-current-plot-pen "random" plot random-score / (num-random-games) ] if num-defect-games > 0 [ set-current-plot-pen "defect" plot defect-score / (num-defect-games) ] if num-cooperate-games > 0 [ set-current-plot-pen "cooperate" plot cooperate-score / (num-cooperate-games) ] if num-tit-for-tat-games > 0 [ set-current-plot-pen "tit-for-tat" plot tit-for-tat-score / (num-tit-for-tat-games) ] if num-unforgiving-games > 0 [ set-current-plot-pen "unforgiving" plot unforgiving-score / (num-unforgiving-games) ] if num-unknown-games > 0 [ set-current-plot-pen "unknown" plot unknown-score / (num-unknown-games) ] if num-tit-for-two-tats-games > 0 [ set-current-plot-pen "tit-for-two-tats" plot tit-for-two-tats-score / (num-tit-for-two-tats-games) ] if num-tit-for-three-tats-games > 0 [ set-current-plot-pen "tit-for-three-tats" plot tit-for-three-tats-score / (num-tit-for-three-tats-games) ] if num-two-tits-for-tat-games > 0 [ set-current-plot-pen "two-tits-for-tat" plot two-tits-for-tat-score / (num-two-tits-for-tat-games) ] if num-three-tits-for-tat-games > 0 [ set-current-plot-pen "three-tits-for-tat" plot three-tits-for-tat-score / (num-three-tits-for-tat-games) ] if num-majority-games > 0 [ set-current-plot-pen "majority" plot majority-score / (num-majority-games) ] end ;; This updates the population plot. to do-popplot set-current-plot "Population sizes" set-current-plot-pen "random-pop" plot n-random set-current-plot-pen "defect-pop" plot n-defect set-current-plot-pen "cooperate-pop" plot n-cooperate set-current-plot-pen "tit-for-tat-pop" plot n-tit-for-tat set-current-plot-pen "unforgiving-pop" plot n-unforgiving set-current-plot-pen "unknown-pop" plot n-unknown set-current-plot-pen "tit-for-two-tats-pop" plot n-tit-for-two-tats set-current-plot-pen "tit-for-three-tats-pop" plot n-tit-for-three-tats set-current-plot-pen "two-tits-for-tat-pop" plot n-two-tits-for-tat set-current-plot-pen "three-tits-for-tat-pop" plot n-three-tits-for-tat set-current-plot-pen "majority-pop" plot n-majority end ;; This counts the population sizes for next round. to count-to-be-kids ifelse sumkids > 0 [ set numkids-random count-turtles * num-random * random-avg-score / sumkids set numkids-cooperate count-turtles * num-cooperate * cooperate-avg-score / sumkids set numkids-defect count-turtles * num-defect * defect-avg-score / sumkids set numkids-tit-for-tat count-turtles * num-tit-for-tat * tit-for-tat-avg-score / sumkids set numkids-unforgiving count-turtles * num-unforgiving * unforgiving-avg-score / sumkids set numkids-unknown count-turtles * num-unknown * unknown-avg-score / sumkids set numkids-tit-for-two-tats count-turtles * num-tit-for-two-tats * tit-for-two-tats-avg-score / sumkids set numkids-tit-for-three-tats count-turtles * num-tit-for-three-tats * tit-for-three-tats-avg-score / sumkids set numkids-two-tits-for-tat count-turtles * num-two-tits-for-tat * two-tits-for-tat-avg-score / sumkids set numkids-three-tits-for-tat count-turtles * num-three-tits-for-tat * three-tits-for-tat-avg-score / sumkids set numkids-majority count-turtles * num-majority * majority-avg-score / sumkids ] [ set numkids-random 0 set numkids-cooperate 0 set numkids-defect 0 set numkids-tit-for-tat 0 set numkids-unforgiving 0 set numkids-unknown 0 set numkids-tit-for-two-tats 0 set numkids-tit-for-three-tats 0 set numkids-two-tits-for-tat 0 set numkids-three-tits-for-tat 0 set numkids-majority 0 ] end ;; Sets number of turtles for next round to set-new-n let difference-random ceiling numkids-random - numkids-random ifelse random-float 1 > difference-random [set n-random ceiling numkids-random] [set n-random floor numkids-random] let difference-cooperate ceiling numkids-cooperate - numkids-cooperate ifelse random-float 1 > difference-cooperate [set n-cooperate ceiling numkids-cooperate] [set n-cooperate floor numkids-cooperate] let difference-defect ceiling numkids-defect - numkids-defect ifelse random-float 1 > difference-defect [set n-defect ceiling numkids-defect] [set n-defect floor numkids-defect] let difference-tit-for-tat ceiling numkids-tit-for-tat - numkids-tit-for-tat ifelse random-float 1 > difference-tit-for-tat [set n-tit-for-tat ceiling numkids-tit-for-tat] [set n-tit-for-tat floor numkids-tit-for-tat] let difference-unforgiving ceiling numkids-unforgiving - numkids-unforgiving ifelse random-float 1 > difference-unforgiving [set n-unforgiving ceiling numkids-unforgiving] [set n-unforgiving floor numkids-unforgiving] let difference-unknown ceiling numkids-unknown - numkids-unknown ifelse random-float 1 > difference-unknown [set n-unknown ceiling numkids-unknown] [set n-unknown floor numkids-unknown] let difference-tit-for-two-tats ceiling numkids-tit-for-two-tats - numkids-tit-for-two-tats ifelse random-float 1 > difference-tit-for-two-tats [set n-tit-for-two-tats ceiling numkids-tit-for-two-tats] [set n-tit-for-two-tats floor numkids-tit-for-two-tats] let difference-tit-for-three-tats ceiling numkids-tit-for-three-tats - numkids-tit-for-three-tats ifelse random-float 1 > difference-tit-for-three-tats [set n-tit-for-three-tats ceiling numkids-tit-for-three-tats] [set n-tit-for-three-tats floor numkids-tit-for-three-tats] let difference-two-tits-for-tat ceiling numkids-two-tits-for-tat - numkids-two-tits-for-tat ifelse random-float 1 > difference-two-tits-for-tat [set n-two-tits-for-tat ceiling numkids-two-tits-for-tat] [set n-two-tits-for-tat floor numkids-two-tits-for-tat] let difference-three-tits-for-tat ceiling numkids-three-tits-for-tat - numkids-three-tits-for-tat ifelse random-float 1 > difference-three-tits-for-tat [set n-three-tits-for-tat ceiling numkids-three-tits-for-tat] [set n-three-tits-for-tat floor numkids-three-tits-for-tat] let difference-majority ceiling numkids-majority - numkids-majority ifelse random-float 1 > difference-majority [set n-majority ceiling numkids-majority] [set n-majority floor numkids-majority] end ;; This helps you by printing average scores for strategies to output field. ;;You can then export the statistics to spreadsheet program for closer examination. to printscore if num-random-games > 0 [ output-type "Random;" output-type i output-type ";" output-type random-score / (num-random-games) output-print ";" ] if num-defect-games > 0 [ output-type "D;" output-type i output-type ";" output-type defect-score / (num-defect-games) output-print ";" ] if num-cooperate-games > 0 [ output-type "C;" output-type i output-type ";" output-type cooperate-score / (num-cooperate-games) output-print ";" ] if num-tit-for-tat-games > 0 [ output-type "TFT;" output-type i output-type ";" output-type tit-for-tat-score / (num-tit-for-tat-games) output-print ";" ] if num-unforgiving-games > 0 [ output-type "unforgiving;" output-type i output-type ";" output-type unforgiving-score / (num-unforgiving-games) output-print ";" ] if num-unknown-games > 0 [ output-type "unknown;" output-type i output-type ";" output-type unknown-score / (num-unknown-games) output-print ";" ] if num-tit-for-two-tats-games > 0 [ output-type "TF2T;" output-type i output-type ";" output-type tit-for-two-tats-score / (num-tit-for-two-tats-games) output-print ";" ] if num-tit-for-three-tats-games > 0 [ output-type "TF3T;" output-type i output-type ";" output-type tit-for-three-tats-score / (num-tit-for-three-tats-games) output-print ";" ] if num-two-tits-for-tat-games > 0 [ output-type "T2FT;" output-type i output-type ";" output-type two-tits-for-tat-score / (num-two-tits-for-tat-games) output-print ";" ] if num-three-tits-for-tat-games > 0 [ output-type "T3FT;" output-type i output-type ";" output-type three-tits-for-tat-score / (num-three-tits-for-tat-games) output-print ";" ] if num-majority-games > 0 [ output-type "majority;" output-type i output-type ";" output-type majority-score / (num-majority-games) output-print ";" ] end ;; Runs a full test for current population of strategies. ;; Examines population for all different values for mistakehearing. to testdifvaluesmistake clear-output set i 0 let valueslist [] repeat 101 [ set valueslist lput i valueslist set i i + 1 ] set i 0 repeat 101 [ set counter 0 set mistakehearing-prob i setup repeat maxcounter [ clear-last-round ask turtles [ partner-up ] ;;have turtles try to find a partner let partnered-turtles turtles with [ partnered? ] ask partnered-turtles [ select-action ] ;;all partnered turtles select action ask partnered-turtles [ play-a-round ] do-bookkeeping set counter counter + 1 display ;; Updates the screen ] do-popplot printscore set i i + 1 ] end ;; Runs a full test for current population of strategies. ;; Examines population for all different values for tremblinghand. to testdifvaluestremble clear-output set i 0 let valueslist [] repeat 101 [ set valueslist lput i valueslist set i i + 1 ] set i 0 repeat 101 [ set counter 0 set tremblinghand-prob i setup repeat maxcounter [ clear-last-round ask turtles [ partner-up ] ;;have turtles try to find a partner let partnered-turtles turtles with [ partnered? ] ask partnered-turtles [ select-action ] ;;all partnered turtles select action ask partnered-turtles [ play-a-round ] do-bookkeeping set counter counter + 1 display ;; Updates the screen ] do-popplot printscore set i i + 1 ] end ; Copyright 2002 Uri Wilensky. All rights reserved. ; The full copyright notice is in the Information tab. ; Expanded by Lasse Lindqvist. @#$#@#$#@ GRAPHICS-WINDOW 566 25 896 376 4 4 35.6 1 10 1 1 1 0 1 1 1 -4 4 -4 4 1 1 1 counter BUTTON 8 19 86 62 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL PLOT -2 404 339 677 Average Payoff Iterations Ave Payoff 0.0 10.0 0.0 5.0 true true PENS "random" 1.0 0 -7500403 true "cooperate" 1.0 0 -2674135 true "defect" 1.0 0 -13345367 true "tit-for-tat" 1.0 0 -13840069 true "unforgiving" 1.0 0 -14835848 true "unknown" 1.0 0 -5825686 true "majority" 1.0 0 -1184463 true "two-tits-for-tat" 1.0 0 -10899396 true "three-tits-for-tat" 1.0 0 -6459832 true "tit-for-two-tats" 1.0 0 -8630108 true "tit-for-three-tats" 1.0 0 -955883 true BUTTON 85 19 174 62 NIL go T 1 T OBSERVER NIL NIL NIL NIL SLIDER 8 61 134 94 n-random n-random 0 100 0 1 1 NIL HORIZONTAL SLIDER 8 94 134 127 n-cooperate n-cooperate 0 100 0 1 1 NIL HORIZONTAL SLIDER 8 127 134 160 n-defect n-defect 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 61 259 94 n-tit-for-tat n-tit-for-tat 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 94 259 127 n-unforgiving n-unforgiving 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 127 259 160 n-unknown n-unknown 0 100 0 1 1 NIL HORIZONTAL TEXTBOX 14 247 180 387 PAYOFF:\n Partner \nTurtle C D\n-------------------------\n C 3 0 \n-------------------------\n D 5 1\n-------------------------\n(C = Cooperate, D = Defect) 11 0.0 0 BUTTON 174 19 260 62 go once go NIL 1 T OBSERVER NIL NIL NIL NIL SLIDER 8 158 134 191 n-tit-for-two-tats n-tit-for-two-tats 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 158 259 191 n-tit-for-three-tats n-tit-for-three-tats 0 100 0 1 1 NIL HORIZONTAL SLIDER 8 189 134 222 n-two-tits-for-tat n-two-tits-for-tat 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 189 259 222 n-three-tits-for-tat n-three-tits-for-tat 0 100 0 1 1 NIL HORIZONTAL SLIDER 133 222 259 255 n-majority n-majority 0 100 0 1 1 NIL HORIZONTAL BUTTON 259 19 363 63 New Round do-avg-score\ncount-to-be-kids\nset-new-n NIL 1 T OBSERVER NIL N NIL NIL INPUTBOX 261 64 391 124 maxcounter 10000 1 0 Number SLIDER 393 62 565 95 tremblinghand-prob tremblinghand-prob 0 100 0 1 1 NIL HORIZONTAL SLIDER 393 93 565 126 mistakehearing-prob mistakehearing-prob 0 100 0 1 1 NIL HORIZONTAL BUTTON 363 19 468 63 Do evolution do-popdyn T 1 T OBSERVER NIL Y NIL NIL PLOT 339 404 732 677 Population sizes Number of rounds Population Size 0.0 10.0 0.0 10.0 true true PENS "random-pop" 1.0 0 -7500403 true "cooperate-pop" 1.0 0 -2674135 true "defect-pop" 1.0 0 -13345367 true "tit-for-tat-pop" 1.0 0 -13840069 true "unforgiving-pop" 1.0 0 -14835848 true "unknown-pop" 1.0 0 -5825686 true "majority-pop" 1.0 0 -1184463 true "two-tits-for-tat-pop" 1.0 0 -10899396 true "three-tits-for-tat-pop" 1.0 0 -6459832 true "tit-for-two-tats-pop" 1.0 0 -8630108 true "tit-for-three-tats-pop" 1.0 0 -955883 true BUTTON 467 19 565 63 Reset plot set-current-plot \"Population sizes\"\nclear-plot\ndo-popplot NIL 1 T OBSERVER NIL NIL NIL NIL OUTPUT 260 130 562 285 12 BUTTON 240 318 564 351 Test population for different values of mistakehearing testdifvaluesmistake NIL 1 T OBSERVER NIL NIL NIL NIL BUTTON 240 286 564 319 Test population for different values of tremblinghand testdifvaluestremble NIL 1 T OBSERVER NIL NIL NIL NIL BUTTON 163 254 259 287 NIL do-popplot NIL 1 T OBSERVER NIL NIL NIL NIL @#$#@#$#@ WHAT IS IT? ----------- This model is a multiplayer version of the iterated prisoner's dilemma. It is intended to explore the strategic implications that emerge when the world consists entirely of prisoner's dilemma like interactions. If you are unfamiliar with the basic concepts of the prisoner's dilemma or the iterated prisoner's dilemma, please refer to the PD BASIC and PD TWO PERSON ITERATED models found in the PRISONER'S DILEMMA suite. HOW IT WORKS ------------ The PD N PERSON ITERATED model demonstrates an interesting concept: When interacting with someone over time in a prisoner's dilemma scenario, it is possible to tune your strategy to do well with theirs. Each possible strategy has unique strengths and weaknesses that appear through the course of the game. For instance, always defect does best of any against the random strategy, but poorly against itself. Tit-for-tat does poorly with the random strategy, but well with itself. This makes it difficult to determine a single "best" strategy. One such approach to doing this is to create a world with multiple agents playing a variety of strategies in repeated prisoner's dilemma situations. This model does just that. The turtles with different strategies wander around randomly until they find another turtle to play with. (Note that each turtle remembers their last interaction with each other turtle. While some strategies don't make use of this information, other strategies do.) Payoffs ------- When two turtles interact, they display their respective payoffs as labels. Each turtle's payoff for each round will determined as follows: | | Partner's Action | Turtle's | | Action | C D | ------------|----------------- | C | 3 0 | ------------|----------------- | D | 5 1 | ------------|----------------- | (C = Cooperate, D = Defect) (Note: This way of determining payoff is the opposite of how it was done in the PD BASIC model. In PD BASIC, you were awarded something bad- jail time. In this model, something good is awarded- money.) HOW TO USE IT -------------- Buttons: SETUP: Setup the world to begin playing the multi-person iterated prisoner's dilemma. The number of turtles and their strategies are determined by the slider values. GO: Have the turtles walk around the world and interact. GO ONCE: Same as GO except the turtles only take one step. NEW ROUND: You can calculate new population sizes for each strategy according to how they have managed in the game. First, stop the simulation, then press "New Round" and this sets new population sizes according to simple evolutionary equations. (New amount = Old population size * Old amount * Avg points of strategy / SUM of every strategy(Old amount * Avg points of strategy)) New population sizes are rounded to the nearest integer. Note: It is possible for one strategy to achieve more turtles than is the maximum on the slider. Be careful with this. Inputs: MAXTICKS - This is the maximux number of games that are to be played between turtles before the simulation stops. You can set this to any positive(!) integer. The only limit is the one set by NetLogo programming language (2^53, about 9 quadrillion). DO-POPPLOT - This is just to help you plot population sizes if you need to do it right now and then. RESET PLOT - Does what it says. Resets the population plot. TEST POPULATION FOR DIFFERENT VALUES OF TREMBLINGHAND - Try this out, and model simulates the population with every possible value of trembling hand. It gives you nice output to export to Spreadsheet if you like. TEST POPULATION FOR DIFFERENT VALUES OF MISTAKEHEARING - Try this out, and model simulates the population with every possible value of trembling hand. It gives you nice output to export to Spreadsheet if you like. Sliders: TREMBLINGHAND-PROB - This is the probability that turtle makes a mistake when it tries to choose between co-op and defect. Nota that unforgiving cannot make mistakes. You can change it in the code if you like. MISTAKEHEARING-PROB - This is the probability that turtle makes a mistake in observing what its opponent chose last time. Turtle still gets the amount of points it should, but it thinks that the opponent defected when it really cooperated or the other way around. With mistakehearing-prob unequale to zero, for example tit-for-tat-strategies can get into vicious revenge-cycles when one of them mistakes opponents coop for defection. N-STRATEGY: Multiple sliders exist with the prefix N- then a strategy name (e.g., n-cooperate). Each of these determines how many turtles will be created that use the STRATEGY. Strategy descriptions are found below: Strategies: RANDOM - randomly cooperate or defect COOPERATE - always cooperate DEFECT - always defect TIT-FOR-TAT - If an opponent cooperates on this interaction cooperate on the next interaction with them. If an opponent defects on this interaction, defect on the next interaction with them. Initially cooperate. UNFORGIVING - Cooperate until an opponent defects once, then always defect in each interaction with them. UNKNOWN - This strategy is included to help you try your own strategies. It currently defaults to Tit-for-Tat. TWO-TITS-FOR-TAT - Cooperates, unless opponent has defected in previous interaction or before that. THREE-TITS-FOR-TAT - Cooperates, unless opponent has defected in any of the three previous interactions. TIT-FOR-TWO-TATS - Cooperate if opponent has cooperated in at least one of previous two interactions. Start with cooperation. TIT-FOR-THREE-TATS - Cooperate if opponent has cooperated in at least one of previous three interactions. Start with cooperation. MAJORITY - Cooperate if opponent has cooperated in majority of three previous interactions. Starts with cooperation. Plots: AVERAGE-PAYOFF - The average payoff of each strategy in an interaction vs. the number of iterations. This is a good indicator of how well a strategy is doing relative to the maximum possible average of 5 points per interaction. POPULATION SIZES - If you use Do-evolution, this plots the population sizes after every round. THINGS TO NOTICE ---------------- Set all the number of player for each strategy to be equal in distribution. For which strategy does the average-payoff seem to be highest? Do you think this strategy is always the best to use or will there be situations where other strategy will yield a higher average-payoff? Set the number of n-cooperate to be high, n-defects to be equivalent to that of n-cooperate, and all other players to be 0. Which strategy will yield the higher average-payoff? Set the number of n-tit-for-tat to be high, n-defects to be equivalent to that of n-tit-for-tat, and all other playerst to be 0. Which strategy will yield the higher average-payoff? What do you notice about the average-payoff for tit-for-tat players and defect players as the iterations increase? Why do you suppose this change occurs? Set the number n-tit-for-tat to be equal to the number of n-cooperate. Set all other players to be 0. Which strategy will yield the higher average-payoff? Why do you suppose that one strategy will lead to higher or equal payoff? THINGS TO TRY -------------- 1. Observe the results of running the model with a variety of populations and population sizes. For example, can you get cooperate's average payoff to be higher than defect's? Can you get Tit-for-Tat's average payoff higher than cooperate's? What do these experiments suggest about an optimal strategy? 2. Currently the UNKNOWN strategy defaults to TIT-FOR-TAT. Modify the UNKOWN and UNKNOWN-HISTORY-UPDATE procedures to execute a strategy of your own creation. Test it in a variety of populations. Analyze its strengths and weaknesses. Keep trying to improve it. 3. Relate your observations from this model to real life events. Where might you find yourself in a similar situation? How might the knowledge obtained from the model influence your actions in such a situation? Why? 4. Look at below the playground and you find tremblinghand-prob, which is the probability of making the wrong move. Try changing this with tft-strategies and see what happens. See also the mistakehearing-prob which is the probability of seeing what opponent did the wrong way. What is the difference between these two? EXTENDING THE MODEL --------------------- Relative payoff table - Create a table which displays the average payoff of each strategy when interacting with each of the other strategies. Complex strategies using lists of lists - The strategies defined here are relatively simple, some would even say naive. Create a strategy that uses the PARTNER-HISTORY variable to store a list of history information pertaining to past interactions with each turtle. Currently has history up to 4 interactions. Spatial Relations - Allow turtles to choose not to interact with a partner. Allow turtles to choose to stay with a partner. Environmental resources - include an environmental (patch) resource and incorporate it into the interactions. NETLOGO FEATURES ----------------- Note the use of the TO-REPORT primitive in the function CALC-SCORE to return a number Note the use of lists and turtle ID's to keep a running history of interactions in the PARTNER-HISTORY turtle variable. Note how agent sets that will be used repeatedly are stored when created and reused to increase speed. RELATED MODELS --------------- PD Basic PD Two Person Iterated PD Basic Evolutionary COPYRIGHT NOTICE ---------------- Copyright 2002 Uri Wilensky. All rights reserved. Permission to use, modify or redistribute this model is hereby granted, provided that both of the following requirements are followed: a) this copyright notice is included. b) this model will not be redistributed for profit without permission from Uri Wilensky. Contact Uri Wilensky for appropriate licenses for redistribution for profit. This model was created as part of the projects: PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. The project gratefully acknowledges the support of the National Science Foundation (REPP & ROLE programs) -- grant numbers REC #9814682 and REC-0126227. --- This model and this guide have been expanded by Lasse Lindqvist (lasse.lindqvist@hotmail.com) in 2012. I release all my edits and improvements to public domain. Note that the original copyright of Uri Wilensky still stands. The original version can be found in Netlogo Models Library under Social Science - (unverified) - Prisoner's Dilemma and by choosing PD-N-Person Iterated. 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