;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;; GNU GENERAL PUBLIC LICENSE ;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; MEQU (Market Effects of Quality Uncertainty) ;; MEQU is a model designed to study the effects of quality ;; uncertainty and incomplete information on market dynamics. ;; Copyright (C) 2005 Segismundo S. Izquierdo and Luis R. Izquierdo ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License ;; as published by the Free Software Foundation; either version 2 ;; of the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public License ;; along with this program; if not, write to the Free Software ;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. ;; ;; Contact information: ;; Segis Izquierdo ;; Department of Industrial Organization, ETS Ingenieros Industriales, ;; P del cauce s/n, 47011 Valladolid, Spain. e-mail: segis@eis.uva.es ;; Luis Izquierdo, ;; Macaulay Institute, Craigiebuckler, Aberdeen, AB15 8QH. United Kingdom ;; e-mail: l.izquierdo@macaulay.ac.uk ;;;;;;;;;;;; ;; Breeds ;; ;;;;;;;;;;;; ;; sellers, buyers, and links between buyers, are all turtles ;; links are not necessarily symmetric breeds [sellers buyers links] ;;;;;;;;;;;;;;; ;; Variables ;; ;;;;;;;;;;;;;;; globals [ list-of-sellers ;; sellers ordered by marginal cost list-of-buyers ;; buyers ordered by reservation price sellers-in-round ;; sellers who have sold a product in the session buyers-in-round ;; buyers who have bought a product in the session price traded-units ;; units traded in the session ;; reference quantities are those that would occur ;; in the absence of quality variability reference-price reference-traded-units reference-quality reference-buyers-surplus reference-sellers-surplus ;; average number of buyers reachable by each buyer ;; in an infinite number of steps avg-accessibility ;; variable for drag-and-drop procedure clicked-buyer ;; buyer who was clicked on my-random-seed ] sellers-own [ marginal-cost surplus ] buyers-own [ std-reservation-price quality-expectation reservation-price ;; this is the product of the two variables above unit-bought? ;; boolean quality-of-unit-bought ;; quality of last unit bought surplus ;; stores the list of buyers that this particular buyer links to linkees ;; these variables are used to do the layout force-x force-y ] ;; The direction of the link does matter in this model. links-own [ origin destination ] ;;;;;;;;;;;;;;;;;;;;;;;;; ;;; Buyers Procedures ;;; ;;;;;;;;;;;;;;;;;;;;;;;;; to buy-product-of-quality [q] set unit-bought? true set quality-of-unit-bought q set surplus q * std-reservation-price - price end to update-quality-expectation let nbrs-who-bought filter [unit-bought?-of ?] linkees ; Agents have to update their expectations if and only if: ; a. They care something about themselves and they have bought OR ; b. They care something about their neighbours and their neighbours have bought set quality-expectation quality-expectation + individual-weight * ( ifelse-value unit-bought? [quality-of-unit-bought - quality-expectation] [0] ) + social-weight * ( ifelse-value not empty? nbrs-who-bought [(mean map [quality-of-unit-bought-of ?] nbrs-who-bought) - quality-expectation] [0] ) set reservation-price quality-expectation * std-reservation-price end ;; accessibility is the number of social neighbours that the buyer could reach ;; in a number of steps equal to "num-steps". For instance, if buyer A links only to buyer B, ;; who links only to buyer C, who has no social neighbours, then A's accessibility ;; in one step is 1, and in two steps is 2; B's accessibility in any number of steps is 1, ;; and C's accessibility in any number of steps is 0. to-report accessibility [num-steps] let step 1 let reachable-buyers linkees let old-length 0 let new-length length reachable-buyers while [ new-length != old-length AND step < num-steps] [ set old-length new-length set reachable-buyers remove-duplicates sentence reachable-buyers reduce [sentence ?1 ?2] map [ linkees-of ?] reachable-buyers set new-length (length reachable-buyers) set step (step + 1) ] report new-length - ifelse-value (member? self reachable-buyers) [1] [0] end ;;;;;;;;;;;;;;;;;;;;;;;; ;;; Setup Procedures ;;; ;;;;;;;;;;;;;;;;;;;;;;;; ;; the following procedure is called when the model is first loaded to startup setup end to setup clear-all set my-random-seed new-seed ; generate a new seed random-seed my-random-seed ; use the new seed make-sellers make-buyers set-default-shape links "line" build-initial-network calculate-reference-values setup-graphs end to make-sellers set-default-shape sellers "person business" let i 1 create-custom-sellers num-sellers [ set marginal-cost i set color yellow ;; spread them out at the bottom of the screen set xcor (i * screen-size-x / num-sellers - screen-edge-x) set ycor (- screen-edge-y) set i (i + 1) ] end to make-buyers set-default-shape buyers "person" let i 1 create-custom-buyers num-buyers [ set std-reservation-price i set quality-expectation 1 set reservation-price i set linkees [] ;; empty list ;; buyers are automatically created with evenly spaced headings, ;; so if they just move forward they will form a circle fd screen-edge-x - 2 set i (i + 1) ] end ;; reference values are those that would occur ;; in the absence of quality variability to calculate-reference-values create-supply create-demand ;; draw reference supply and demand set-current-plot "market" set-current-plot-pen "ref-demand" foreach list-of-buyers [ plot reservation-price-of ? ] set-current-plot-pen "supply" foreach list-of-sellers [ plot marginal-cost-of ? ] calculate-price-and-traded-units set reference-price price set reference-traded-units traded-units set reference-quality mean map [quality-expectation-of ?] list-of-buyers set reference-buyers-surplus sum map [std-reservation-price-of ?] buyers-in-round - price * traded-units set reference-sellers-surplus price * traded-units - sum map [marginal-cost-of ?] sellers-in-round end to setup-graphs set-current-plot "market" set-plot-x-range 0 max list num-buyers num-sellers set-plot-y-range 0 max sentence map [reservation-price-of ?] list-of-buyers map [marginal-cost-of ?] list-of-sellers ;; drag-and-drop related variables set clicked-buyer nobody end ;;;;;;;;;;;;;;;;;;;;;; ;;; Main Procedure ;;; ;;;;;;;;;;;;;;;;;;;;;; to go create-supply create-demand calculate-price-and-traded-units exchange-goods update-graphs ; BEHAVIORSPACE ;if traded-units = 0 [ ; user-message "No more units traded" ; stop ;] ask buyers [update-quality-expectation] ;; social network dynamics ;; create or delete links, as required let actual-num-links count links if num-links != actual-num-links [ ifelse num-links > actual-num-links [ make-links (num-links - actual-num-links) ] [ delete-links (actual-num-links - num-links) ] ] end ;;;;;;;;;;;;;;;;;;;;;;;;;; ;;; Runtime Procedures ;;; ;;;;;;;;;;;;;;;;;;;;;;;;;; to create-supply set list-of-sellers sort-by [marginal-cost-of ?1 < marginal-cost-of ?2] values-from sellers [self] end to create-demand set list-of-buyers sort-by [reservation-price-of ?1 > reservation-price-of ?2 ] values-from buyers [self] end to calculate-price-and-traded-units set sellers-in-round [] set buyers-in-round [] set traded-units 0 ask buyers [ set unit-bought? false ] ;; calculate the number of traded units, and ;; create the lists of buyers and sellers in the round while [traded-units < num-buyers and traded-units < num-sellers and reservation-price-of item traded-units list-of-buyers >= marginal-cost-of item traded-units list-of-sellers ] [ set sellers-in-round lput (item traded-units list-of-sellers) sellers-in-round set buyers-in-round lput (item traded-units list-of-buyers) buyers-in-round set traded-units traded-units + 1 ] ;; if there's going to be any trade, calculate the price. ;; This price-setting formula takes into account the satisfied supply and demand ;; and the pressure of the unsatisfied supply and demand ifelse traded-units > 0 [ let min-price ifelse-value (num-sellers = traded-units) [ reservation-price-of item (traded-units - 1) list-of-buyers ] [ min list (reservation-price-of item (traded-units - 1) list-of-buyers) (marginal-cost-of item (traded-units) list-of-sellers) ] let max-price ifelse-value (num-buyers = traded-units) [ marginal-cost-of item (traded-units - 1) list-of-sellers ] [ max list (marginal-cost-of item (traded-units - 1) list-of-sellers) (reservation-price-of item (traded-units) list-of-buyers) ] set price (min-price + max-price) / 2 ] ; BEHAVIORSPACE [set price 0] ; should be "NULL" end ;; goods are exchanged and the quality of every product is uncovered to exchange-goods if quality-distribution = "uniform" [ let range 0 ;; Doing what comes next every time-step is inefficient ;; but it has to be done like this to allow the user to ;; change the distribution at run-time set quality-variance min list quality-variance ((2 ^ 2) / 12) set range (sqrt (12 * quality-variance)) foreach buyers-in-round [ ask ? [buy-product-of-quality (1 - (range / 2) + random-float range)] ] stop ] if quality-distribution = "(trimmed) normal" [ foreach buyers-in-round [ let quality-of-product random-normal 1 quality-variance if quality-of-product < 0 [ set quality-of-product 0 ] if quality-of-product > 2 [ set quality-of-product 2 ] ask ? [buy-product-of-quality quality-of-product] ] stop ] if quality-distribution = "exponential" [ set quality-variance 1 foreach buyers-in-round [ ask ? [buy-product-of-quality random-exponential 1] ] stop ] end ;;;;;;;;;;;;;;;;;;;;;;; ;;; Link Operations ;;; ;;;;;;;;;;;;;;;;;;;;;;; to build-initial-network if network-structure = "random" [ build-random-network stop] if network-structure = "preferential attachment" [ build-preferential-attachment-network pref-attachment-links stop] if network-structure = "double ring" [ build-double-ring-network stop] if network-structure = "star" [ build-star-network stop] end to build-random-network ;; you cannot create more directed links than (num-buyers * (num-buyers - 1)) set num-links min list num-links (num-buyers * (num-buyers - 1)) if-else num-links < (0.72 * (num-buyers * (num-buyers - 1))) [ make-links num-links ] [ ;; make a fully connected network ask buyers [without-interruption[ ask buyers with [self != myself] [make-link-from-me-to myself] ]] ;; The following commented code is slower but allows to see the network formation ;let buyers-list values-from buyers [self] ;foreach buyers-list [ ;let tmp-buyer ? ;foreach (remove tmp-buyer buyers-list) [ make-link tmp-buyer ?] ;] ;; and randomly delete the necessary links delete-links ((num-buyers * (num-buyers - 1)) - num-links) ] end to build-preferential-attachment-network [n-of-edges-per-new-vertex] ;; This is Barabási and Albert's "preferential attachment" model of network growth (See Newman, ;; "The structure and function of complex networks", sec. 7B). Basically, each new buyer selects ;; "pref-attachment-links" other buyers to link to, who are selected with probability proportional to ;; their number of existing (incoming and outgoing) links. let vertices shuffle values-from buyers [self] if n-of-edges-per-new-vertex > 0 [ make-link (first vertices) (item 1 vertices) let list-of-vertices-repeated list 0 1 let n-of-vertices-in-the-network 2 repeat (length vertices) - n-of-vertices-in-the-network [ let vertices-linked [] while [(length vertices-linked < n-of-edges-per-new-vertex) and (length vertices-linked < n-of-vertices-in-the-network)] [ let vertex-to-link random-one-of list-of-vertices-repeated if not member? vertex-to-link vertices-linked [ set vertices-linked lput vertex-to-link vertices-linked ] ] ;; now link the vertices let new-vertex (item n-of-vertices-in-the-network vertices) foreach vertices-linked [make-link new-vertex (item ? vertices)] set list-of-vertices-repeated sentence list-of-vertices-repeated vertices-linked repeat (length vertices-linked) [ set list-of-vertices-repeated lput n-of-vertices-in-the-network list-of-vertices-repeated ] set n-of-vertices-in-the-network (n-of-vertices-in-the-network + 1) ] ] set num-links count links plot-accessibility end to build-double-ring-network ;; randomly seated in a round table and links to the one on the right and the one on the left let vertices shuffle values-from buyers [self] (foreach vertices (fput last vertices but-last vertices) (lput first vertices but-first vertices) [ make-link ?1 ?2 make-link ?1 ?3 ] ) set num-links count links plot-accessibility end to build-star-network ;; one buyer is randomly chosen. She links to all the others and all the others link to her. let centre random-one-of buyers let others values-from (buyers with [self != centre]) [self] foreach others [ make-link ? centre make-link centre ? ] set num-links count links plot-accessibility end to make-links [n-links] ;; you cannot create more directed links than (num-buyers * (num-buyers - 1)) let links-to-create min list n-links (num-buyers * (num-buyers - 1) - count links) repeat links-to-create [ add-random-link set num-links count links ] set num-links count links plot-accessibility end to make-link-from-me-to [linkee] if member? linkee linkees [ user-message "There is already a link from me (" + self + ") to " + linkee stop ] hatch-links 1 [ set origin myself set destination linkee set color color-of myself reposition-link ] ;; add linkee to the linker's list of linkees set linkees fput linkee linkees if show-network-formation [ repeat 20 [layout] plot-accessibility ] end ;; The algorithm for the following procedure has been borrowed from the ;; model "Giant Component", in the "Models library". ;; The copyright for this procedure is included at the bottom of this file ;; pick a random missing link and create it to add-random-link let potential-linker random-one-of buyers let potential-linkee random-one-of buyers with [potential-linker != self] ifelse member? potential-linkee linkees-of potential-linker ;; if there's already a link there, then go back ;; and pick two new buyers [ add-random-link ] ;; else, go ahead and make it [ make-link potential-linker potential-linkee ] end ;; The algorithm for the following procedure has been borrowed from the ;; model "Giant Component", in the "Models library". ;; The copyright for this procedure is included at the bottom of this file ;; makes a link from linker to linkee to make-link [linker linkee] if member? linkee linkees-of linker [ user-message "There is already a link from " + linker + " to " + linkee stop ] create-custom-links 1 [ set origin linker set destination linkee set color color-of linker reposition-link ] ;; add linkee to the linker's list of linkees set linkees-of linker fput linkee linkees-of linker if show-network-formation [ repeat 20 [layout] plot-accessibility ] end ;; deletes n-links links at random to delete-links [n-links] let n-links-to-delete min list n-links (count links) let links-to-delete random-n-of n-links-to-delete links ask links-to-delete [ without-interruption [ set (linkees-of origin) remove destination (linkees-of origin) die ] ] plot-accessibility end ;; The algorithm for the following procedure has been borrowed from the ;; model "Giant Component", in the "Models library". ;; The copyright for this procedure is included at the bottom of this file ;; repositions and resizes the link according to the position of the ;; buyers to reposition-link ;; link procedure setxy (xcor-of origin) (ycor-of origin) set size distance-nowrap destination ;; watch out for special case where origin and destination are ;; at the same place if size != 0 [ ;; position link at midpoint between origin and destination set heading towards-nowrap destination jump size / 2 ] end ;;;;;;;;;;;;;;;; ;;; Plotting ;;; ;;;;;;;;;;;;;;;; to update-graphs plot-market plot-price plot-volume plot-average-quality plot-sellers-surplus plot-buyers-surplus end to plot-market set-current-plot "market" set-current-plot-pen "demand" plot-pen-reset foreach list-of-buyers [ plot reservation-price-of ? ] end to plot-price set-current-plot "price" set-current-plot-pen "price" ifelse price != "NULL" [ plot price ] [ set-plot-pen-color red plot 0 ] set-current-plot-pen "ref-price" plot reference-price end to plot-volume set-current-plot "volume" set-current-plot-pen "volume" plot traded-units set-current-plot-pen "ref-volume" plot reference-traded-units end to plot-average-quality set-current-plot "average expected quality" set-current-plot-pen "avg exp q" plot avg-exp-quality set-current-plot-pen "ref-quality" plot reference-quality end to-report avg-exp-quality report mean map [quality-expectation-of ?] list-of-buyers end to plot-buyers-surplus set-current-plot "buyers surplus" set-current-plot-pen "buyers surplus" plot buyers-surplus set-current-plot-pen "ref-surplus" plot reference-buyers-surplus end to-report buyers-surplus report sum map [surplus-of ?] buyers-in-round end to plot-sellers-surplus set-current-plot "sellers surplus" set-current-plot-pen "sellers surplus" plot sellers-surplus set-current-plot-pen "ref-surplus" plot reference-sellers-surplus end to-report sellers-surplus report ifelse-value (price != "NULL") [ price * traded-units - sum map [marginal-cost-of ?] sellers-in-round ] [ 0 ] end to plot-accessibility let steps accessibility-steps if accessibility-steps = "Infinity" [set steps num-buyers] let accessibility-list values-from buyers [accessibility steps] let max-accessibility max accessibility-list set-current-plot "Accessibility Distribution" set-plot-x-range 0 (max-accessibility + 1) ;; + 1 to make room for the width of the last bar histogram-list accessibility-list set avg-accessibility mean accessibility-list end to-report total-surplus report sellers-surplus + buyers-surplus end to-report marginal-costs report values-from sellers [marginal-cost] end to-report reservation-prices report values-from buyers [reservation-price] end ;;;;;;;;;;;;;; ;;; Layout ;;; ;;;;;;;;;;;;;; ;; The algorithm for the following procedure has been borrowed from the ;; model "Giant Component", in the "Models library". ;; The copyright for this procedure is included at the bottom of this file to layout no-display ;; these values are arbitrarily chosen to give a good layout ;; for typical model settings let spring-constant 0.2 let natural-length 9.0 let repulsion-constant 1.0 ;; reset force-x and force-y ask buyers [ set force-x 0 set force-y 0 ] ;; add the forces due to the springs without-interruption ;; process links one at a time, not concurrently [ ask links [ let spring-force (spring-constant * (size - natural-length)) ;; take care of zero sized spring ifelse size = 0 [ set spring-force spring-constant * natural-length ;; we know force but dont know the direction in which to apply it ;; make an arbitrary choice of direction ( postive and negative x direction) ask origin [set force-x force-x + spring-force] ask destination [set force-x force-x - spring-force] ] [ ask origin [ set force-x force-x + spring-force * sin towards-nowrap destination-of myself set force-y force-y + spring-force * cos towards-nowrap destination-of myself ] ask destination [ set force-x force-x + spring-force * sin towards-nowrap origin-of myself set force-y force-y + spring-force * cos towards-nowrap origin-of myself ] ] ] ] ;; add a force of repulsion between buyers, ;; inversely proportional to square of distance without-interruption ;; process buyers one at a time, not concurrently [ ;; exempt linkless buyers from the force let connected-buyers buyers with [not empty? linkees] ask connected-buyers [ ask connected-buyers with [self != myself] [ let angle 0 let force 0 ifelse xcor = xcor-of myself and ycor = ycor-of myself ;; the two buyers are exactly on top of each other. theoretically ;; this shouldn't occur, but in practice, it might because the world ;; is bounded and buyers can get forced into the corners. not clear ;; how to handle this, so just apply a small arbitrary force in a ;; random direction. [ set angle random-float 360 ;; arbitrary set force repulsion-constant ;; arbitrary ] ;; normal case where buyers aren't on top of each other [ set angle towards-nowrap myself set force repulsion-constant / ((distance-nowrap myself) ^ 2) ] set force-x force-x - force * sin angle set force-y force-y - force * cos angle ] ] ] ;; actually move the buyers ask buyers [ ;; the current layout scheme has an issue where ;; sometimes heavily connected buyers are thrown back and forth. ;; to prevent that we cap the movement of buyers ifelse force-x > 1 [ set force-x 1 ] [ if force-x < -1 [set force-x -1] ] ifelse force-y > 1 [ set force-y 1 ] [ if force-y < -1 [set force-y -1] ] move (xcor + force-x) (ycor + force-y) ] ;; reposition all the links ask links [ reposition-link ] ;; update the display, for smooth animation display end ;; move, but take care not to wrap around link of world to move [x y] ;; buyer procedure ifelse x > screen-edge-x [ set x screen-edge-x ] [ if x < (- screen-edge-x) [ set x (- screen-edge-x) ] ] ifelse y > screen-edge-y [ set y screen-edge-y ] [ if y < (- screen-edge-y + 1) [ set y (- screen-edge-y + 1) ] ] setxy x y end to drag-and-drop-buyers ifelse mouse-down? [ ifelse is-agent? clicked-buyer [ ask clicked-buyer [ setxy mouse-xcor mouse-ycor ] ] [ ;; no buyer had been clicked ;; if there are buyers at the current mouse location, then pick one if any? buyers-at round mouse-xcor round mouse-ycor [ set clicked-buyer random-one-of buyers-at round mouse-xcor round mouse-ycor ] ] ask links [ reposition-link ] ] [ ;; mouse not down set clicked-buyer nobody ] end ;; The algorithm for the following procedure has been borrowed from the ;; model "Preferential Attachment", in the "Models library". ;; The copyright for this procedure is included at the bottom of this file ;; resize-buyers, change back and forth from size based on degree to a size of 1 to resize-buyers ifelse ( not (any? buyers with [size > 1]) ) [ ask buyers [ set size sqrt length linkees] ] [ ask buyers [ set size 1 ] ] end ;; The following copyright is included because the coding of some procedures ;; was inspired or copied from models that included this copyright. ; *** NetLogo Model Copyright Notice *** ; ; This model was created as part of the projects: ; PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN ; CLASSROOMS and INTEGRATED SIMULATION AND MODELING ENVIRONMENT. ; The project gratefully acknowllinks the support of the ; National Science Foundation (REPP & ROLE programs) -- grant numbers ; REC #9814682 and REC-0126227. ; ; Copyright 2005 by Uri Wilensky. Updated 2005. 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. ; ; To refer to this model in academic publications, please use: ; Wilensky, U. (2005). NetLogo Preferential Attachment model. ; http://ccl.northwestern.edu/netlogo/models/PreferentialAttachment. ; Center for Connected Learning and Computer-Based Modeling, ; Northwestern University, Evanston, IL. ; ; In other publications, please use: ; Copyright 2005 by Uri Wilensky. All rights reserved. See ; http://ccl.northwestern.edu/netlogo/models/PreferentialAttachment ; for terms of use. ; ; *** End of NetLogo Model Copyright Notice *** @#$#@#$#@ GRAPHICS-WINDOW 292 12 596 337 10 10 14.0 1 10 1 1 1 0 0 0 1 CC-WINDOW 5 596 866 691 Command Center 0 BUTTON 14 10 80 43 NIL setup NIL 1 T OBSERVER T NIL BUTTON 187 10 248 43 NIL go T 1 T OBSERVER NIL NIL BUTTON 104 10 164 43 go-once go NIL 1 T OBSERVER T NIL BUTTON 677 47 764 80 relax network layout T 1 T OBSERVER T NIL BUTTON 599 47 676 80 resize buyers resize-buyers NIL 1 T OBSERVER T NIL SLIDER 153 110 288 143 num-links num-links 0 9900 200 1 1 NIL SLIDER 4 50 108 83 num-sellers num-sellers 0 100 100 1 1 NIL SLIDER 4 85 108 118 num-buyers num-buyers 0 100 100 1 1 NIL BUTTON 765 47 857 80 drag and drop drag-and-drop-buyers T 1 T OBSERVER T NIL SWITCH 599 12 787 45 show-network-formation show-network-formation 1 1 -1000 PLOT 292 339 596 460 price time-step NIL 0.0 10.0 0.0 10.0 true false PENS "price" 1.0 0 -16777216 true "ref-price" 1.0 2 -13840069 true PLOT 292 462 596 582 volume time-step units 0.0 10.0 0.0 10.0 true false PENS "volume" 1.0 0 -16777216 true "ref-volume" 1.0 2 -13840069 true PLOT 4 239 289 460 market quantity price 0.0 10.0 0.0 10.0 false false PENS "supply" 1.0 2 -13345367 true "demand" 1.0 2 -2674135 true "ref-demand" 1.0 2 -13840069 true SLIDER 4 155 128 188 individual-weight individual-weight 0 1 0.4 0.05 1 NIL PLOT 4 462 289 582 average expected quality time-step NIL 0.0 10.0 0.0 0.0 true false PENS "avg exp q" 1.0 0 -16777216 true "ref-quality" 1.0 2 -13840069 true SLIDER 4 120 128 153 social-weight social-weight 0 1 0.4 0.05 1 NIL PLOT 599 87 857 246 Accessibility Distribution # of reachable buyers # of buyers 0.0 2.0 0.0 10.0 true false PENS "default" 1.0 1 -16777216 false MONITOR 763 269 857 318 NIL avg-accessibility 3 1 PLOT 599 339 857 460 sellers surplus time-step NIL 0.0 10.0 0.0 10.0 true false PENS "sellers surplus" 1.0 0 -16777216 true "ref-surplus" 1.0 2 -13840069 true PLOT 599 462 857 582 buyers surplus time-step NIL 0.0 10.0 0.0 10.0 true false PENS "buyers surplus" 1.0 0 -16777216 true "ref-surplus" 1.0 2 -13840069 true CHOOSER 4 192 123 237 quality-distribution quality-distribution "uniform" "(trimmed) normal" "exponential" 0 SLIDER 126 199 246 232 quality-variance quality-variance 0 1 0.33 0.01 1 NIL CHOOSER 153 62 288 107 network-structure network-structure "random" "preferential attachment" "double ring" "star" 0 SLIDER 153 146 288 179 pref-attachment-links pref-attachment-links 0 99 2 1 1 NIL CHOOSER 599 250 708 295 accessibility-steps accessibility-steps 1 2 3 4 5 10 20 "Infinity" 0 BUTTON 599 299 708 332 Update accessibility plot-accessibility NIL 1 T OBSERVER T NIL @#$#@#$#@ Detailed documentation for this model is available at http://www.research.izqui.org/ @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 butterfly true 0 Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240 Polygon -7500403 true true 150 165 89 198 75 225 75 255 105 270 135 255 150 240 Polygon -7500403 true true 139 148 100 105 55 90 25 90 10 105 10 135 25 180 40 195 85 194 139 163 Polygon -7500403 true true 162 150 200 105 245 90 275 90 290 105 290 135 275 180 260 195 215 195 162 165 Polygon -16777216 true false 150 255 135 225 120 150 135 120 150 105 165 120 180 150 165 225 Circle -16777216 true false 135 90 30 Line -16777216 false 150 105 195 60 Line -16777216 false 150 105 105 60 car false 0 Polygon -7500403 true true 300 180 279 164 261 144 240 135 226 132 213 106 203 84 185 63 159 50 135 50 75 60 0 150 0 165 0 225 300 225 300 180 Circle -16777216 true false 180 180 90 Circle -16777216 true false 30 180 90 Polygon -16777216 true false 162 80 132 78 134 135 209 135 194 105 189 96 180 89 Circle -7500403 true true 47 195 58 Circle -7500403 true true 195 195 58 circle false 0 Circle -7500403 true true 0 0 300 circle 2 false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 coloured line true 0 Line -11221820 false 150 300 150 225 Line -13791810 false 150 225 150 150 Line -13345367 false 150 150 150 75 Line -8630108 false 150 75 150 0 cow false 0 Polygon -7500403 true true 200 193 197 249 179 249 177 196 166 187 140 189 93 191 78 179 72 211 49 209 48 181 37 149 25 120 25 89 45 72 103 84 179 75 198 76 252 64 272 81 293 103 285 121 255 121 242 118 224 167 Polygon -7500403 true true 73 210 86 251 62 249 48 208 Polygon -7500403 true true 25 114 16 195 9 204 23 213 25 200 39 123 cylinder false 0 Circle -7500403 true true 0 0 300 dot false 0 Circle -7500403 true true 90 90 120 face happy false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 255 90 239 62 213 47 191 67 179 90 203 109 218 150 225 192 218 210 203 227 181 251 194 236 217 212 240 face neutral false 0 Circle -7500403 true true 8 7 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Rectangle -16777216 true false 60 195 240 225 face sad false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183 fish false 0 Polygon -1 true false 44 131 21 87 15 86 0 120 15 150 0 180 13 214 20 212 45 166 Polygon -1 true false 135 195 119 235 95 218 76 210 46 204 60 165 Polygon -1 true false 75 45 83 77 71 103 86 114 166 78 135 60 Polygon -7500403 true true 30 136 151 77 226 81 280 119 292 146 292 160 287 170 270 195 195 210 151 212 30 166 Circle -16777216 true false 215 106 30 flag false 0 Rectangle -7500403 true true 60 15 75 300 Polygon -7500403 true true 90 150 270 90 90 30 Line -7500403 true 75 135 90 135 Line -7500403 true 75 45 90 45 flower false 0 Polygon -10899396 true false 135 120 165 165 180 210 180 240 150 300 165 300 195 240 195 195 165 135 Circle -7500403 true true 85 132 38 Circle -7500403 true true 130 147 38 Circle -7500403 true true 192 85 38 Circle -7500403 true true 85 40 38 Circle -7500403 true true 177 40 38 Circle -7500403 true true 177 132 38 Circle -7500403 true true 70 85 38 Circle -7500403 true true 130 25 38 Circle -7500403 true true 96 51 108 Circle -16777216 true false 113 68 74 Polygon -10899396 true false 189 233 219 188 249 173 279 188 234 218 Polygon -10899396 true false 180 255 150 210 105 210 75 240 135 240 house false 0 Rectangle -7500403 true true 45 120 255 285 Rectangle -16777216 true false 120 210 180 285 Polygon -7500403 true true 15 120 150 15 285 120 Line -16777216 false 30 120 270 120 leaf false 0 Polygon -7500403 true true 150 210 135 195 120 210 60 210 30 195 60 180 60 165 15 135 30 120 15 105 40 104 45 90 60 90 90 105 105 120 120 120 105 60 120 60 135 30 150 15 165 30 180 60 195 60 180 120 195 120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195 Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195 line true 0 Line -7500403 true 150 0 150 300 line half true 0 Line -7500403 true 150 0 150 150 pentagon false 0 Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120 person false 0 Circle -7500403 true true 110 5 80 Polygon -7500403 true true 105 90 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 195 90 Rectangle -7500403 true true 127 79 172 94 Polygon -7500403 true true 195 90 240 150 225 180 165 105 Polygon -7500403 true true 105 90 60 150 75 180 135 105 person business false 0 Rectangle -1 true false 120 90 180 180 Polygon -13345367 true false 135 90 150 105 135 180 150 195 165 180 150 105 165 90 Polygon -7500403 true true 120 90 105 90 60 195 90 210 116 154 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 183 153 210 210 240 195 195 90 180 90 150 165 Circle -7500403 true true 110 5 80 Rectangle -7500403 true true 127 76 172 91 Line -16777216 false 172 90 161 94 Line -16777216 false 128 90 139 94 Polygon -13345367 true false 195 225 195 300 270 270 270 195 Rectangle -13791810 true false 180 225 195 300 Polygon -14835848 true false 180 226 195 226 270 196 255 196 Polygon -13345367 true false 209 202 209 216 244 202 243 188 Line -16777216 false 180 90 150 165 Line -16777216 false 120 90 150 165 plant false 0 Rectangle -7500403 true true 135 90 165 300 Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285 Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285 Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210 Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135 Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135 Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60 Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90 square false 0 Rectangle -7500403 true true 30 30 270 270 square 2 false 0 Rectangle -7500403 true true 30 30 270 270 Rectangle -16777216 true false 60 60 240 240 star false 0 Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108 target false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 Circle -7500403 true true 60 60 180 Circle -16777216 true false 90 90 120 Circle -7500403 true true 120 120 60 tree false 0 Circle -7500403 true true 118 3 94 Rectangle -6459832 true false 120 195 180 300 Circle -7500403 true true 65 21 108 Circle -7500403 true true 116 41 127 Circle -7500403 true true 45 90 120 Circle -7500403 true true 104 74 152 triangle false 0 Polygon -7500403 true true 150 30 15 255 285 255 triangle 2 false 0 Polygon -7500403 true true 150 30 15 255 285 255 Polygon -16777216 true false 151 99 225 223 75 224 truck false 0 Rectangle -7500403 true true 4 45 195 187 Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194 Rectangle -1 true false 195 60 195 105 Polygon -16777216 true false 238 112 252 141 219 141 218 112 Circle -16777216 true false 234 174 42 Rectangle -7500403 true true 181 185 214 194 Circle -16777216 true false 144 174 42 Circle -16777216 true false 24 174 42 Circle -7500403 false true 24 174 42 Circle -7500403 false true 144 174 42 Circle -7500403 false true 234 174 42 turtle true 0 Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210 Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105 Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105 Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87 Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210 Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99 wheel false 0 Circle -7500403 true true 3 3 294 Circle -16777216 true false 30 30 240 Line -7500403 true 150 285 150 15 Line -7500403 true 15 150 285 150 Circle -7500403 true true 120 120 60 Line -7500403 true 216 40 79 269 Line -7500403 true 40 84 269 221 Line -7500403 true 40 216 269 79 Line -7500403 true 84 40 221 269 x false 0 Polygon -7500403 true true 270 75 225 30 30 225 75 270 Polygon -7500403 true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 3.0 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed avg-accessibility setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed marginal-costs reservation-prices setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed marginal-costs reservation-prices setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed avg-accessibility setup go price traded-units sellers-surplus buyers-surplus total-surplus avg-exp-quality my-random-seed avg-accessibility @#$#@#$#@