globals[moves ; number of moves so far winner? ; false until someone wins PLAYER-1 ; a player and colored red PLAYER-2 ; the other player and CONNIE both colored blue current-player ; used to control the order of play next-player? ; shows next player ; the following are parts of CONNIE's (Connect4 Informed Engine) brain ; x & y are the built-in Netlogo patch coordinates h ; positive number horizontal coordinate h = x+4 p ; single number patch coordinate p = x+7y+18 n ; counts steps in blue-check and red-check winb ; counts the checkers in a line of 4 patches during blue-check winr ; " " " " " " " " " " red " pblue ; signals the detection of a line of 3 blue checkers pred ; " " " " " " " 3 red " block ; closes and opens the red and blue check results to CONNIE redlist ; single number 'p' patch coordinate list of red checkers bluelist ; single number 'p' patch coordinate list of blue checkers allist ; list of all 'p' used to adjust the column lists as play proceeds column1 ; a list of the checkers in each column by 'p' number column2 ; " " " " " " " " " " " column3 ; " " " " " " " " " " " column4 ; " " " " " " " " " " " column5 ; " " " " " " " " " " " column6 ; " " " " " " " " " " " column7 ; " " " " " " " " " " " ] patches-own [anyone? ; is there a checker here? ] to setup ; setting up the game board and the program for some of CONNIE's brain ca ; clear all set allist [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 ; list of all 'p' showing 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 0] ; patches unused set column1 [1 8 15 22 29 36 0] ; 7 lists of the checkers on the board by 'p' number set column2 [2 9 16 23 30 37 0] ; with the inital condition set to full, plus 0 at the top set column3 [3 10 17 24 31 38 0] ; initial condition set column4 [4 11 18 25 32 39 0] ; " " set column5 [5 12 19 26 33 40 0] ; " " set column6 [6 13 20 27 34 41 0] ; " " set column7 [7 14 21 28 35 42 0] ; " " set bluelist [] ; list of the blue checkers by 'p' number set redlist [] ; " " " red " " " " set block false ; initial condition set next-player? "PLAYER-1" ; " " set winner? false ; " " text-1 ; shows the 'p' values at the patches on the game board ask patches[ifelse pycor + screen-edge-y = 0[ set pcolor grey ; fills the un-needed row set anyone? false ][ set pcolor yellow ; colors the game-board set anyone? false sprout 1[ set shape "circle" ; shapes the game-board set color 9.999 ]]] end to text-1 ; shows the 'p' values at the patches on the game board crt 1 ask turtles [setxy 3 3 plc set plabel "36 37 38 39 40 41 42"] ask turtles [setxy 3 2 plc set plabel "29 30 31 32 33 34 35"] ask turtles [setxy 3 1 plc set plabel "22 23 24 25 26 27 28"] ask turtles [setxy 3 0 plc set plabel "15 16 17 18 19 20 21"] ask turtles [setxy 3 -1 plc set plabel "08 09 10 11 12 13 14"] ask turtles [setxy 3 -2 plc set plabel "01 02 03 04 05 06 07"] end to plc ; sets text color ht set plabel-color 0 end to add-piece [x] ; the button column numbers or xcor's read L to R -3 -2 -1 0 1 2 3 ; which after the transformation h=x+4 becomes 1 2 3 4 5 6 7 locals [ move-ready ; shows that checker is ready to be placed listing ; the list of ycor's y ; vertical coordinate of a patch ] ifelse winner? = true [stop][ ; don't continue if the game is over set move-ready false set listing [-2 -1 0 1 2 3] ; lists the ycor's or row numbers if value-from patch x 3 [anyone?] = false [ ; used to see if there are any legal sites cct 1 [set shape "circle" ; to make a checker without-interruption [ foreach listing [ ask patch x ? [if anyone? = false and move-ready = false [ set y pycor ; y coordinate of the checker set anyone? true ; this patch is now in use set move-ready true ]]]] ifelse remainder (moves + 2) 2 = 0 [ ; creates 1's and 0's to set color red set current-player "PLAYER-1"][ ; sets the order of play set color blue set current-player "PLAYER-2 & CONNIE"] ; player-2 or CONNIE is second to move ifelse color = blue[set next-player? "PLAYER-1"][ set next-player? "PLAYER-2 or CONNIE"] setxy x y ; coordinates of the checker set moves moves + 1 ; the checker is placed ; CONNIE's brain starts in this short section here ; CONNIE's alternative positive number horizontal coordinate is h = x + 4 ; and her alternative single number patch coordinate p = x + 7y + 18, hence the following code: set h x + 4 set p x + (7 * y) + 18 ; also for h from p she uses, ifelse remainder (p + 7) 7 = 0[set h 7][set h remainder (p + 7) 7] ; checkers are listed according to position 'p' and by color, then checked for winning sets of 4 ; and this must be completed for each move, (a checker placed), first for red and then for blue ; but if CONNIE is ON, for blue only after she has made her checks, also because she uses parts of ; the same procedure, 'set block true' in the code below temporarily isolates CONNIE from this code if color = red[ set block true set redlist sort fput p redlist redcheck set block false] ; checks for a red win if color = blue[ set block true set bluelist sort fput p bluelist bluecheck set block false] ; checks for a blue win ]]] ; this section is not CONNIE code ifelse winner? = true [stop][ ifelse moves = 42 [set moves 0 set next-player? "PLAYER-1" print " No More Moves Left - Its a Draw!" print " Hit START PLAY to re-start" stop][ ; CONNIE continues here with the code that removes 'p' numbers from allist as checkers are placed foreach allist[if member? ? redlist = true[set allist remove ? allist]] foreach allist[if member? ? bluelist = true[set allist remove ? allist]] ; then uses allist to remove 'p' numbers of checkers from column lists so that foreach column1[if member? ? allist = false[set column1 remove ? column1]] foreach column2[if member? ? allist = false[set column2 remove ? column2]] foreach column3[if member? ? allist = false[set column3 remove ? column3]] foreach column4[if member? ? allist = false[set column4 remove ? column4]] foreach column5[if member? ? allist = false[set column5 remove ? column5]] foreach column6[if member? ? allist = false[set column6 remove ? column6]] foreach column7[if member? ? allist = false[set column7 remove ? column7]] ; the first 'p' number of a column is available for CONNIE to use to ; test for a blue line of 3 to make into a blue line of 4 (to make an immediate win) if CONNIE = true and remainder (moves + 2) 2 != 0[ if moves = 1[consplay] ; to implement a set play for blue's first move if (first column1) != 0[ set bluelist fput (first column1) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column2) != 0[ set bluelist fput (first column2) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column3) != 0[ set bluelist fput (first column3) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column4) != 0[ set bluelist fput (first column4) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column5) != 0[ set bluelist fput (first column5) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column6) != 0[ set bluelist fput (first column6) bluelist bluecheck set bluelist remove-item 0 bluelist] if (first column7) != 0[ set bluelist fput (first column7) bluelist bluecheck set bluelist remove-item 0 bluelist] ifelse pblue = true[consplay][ ; or to test for a red line of 3 to STOP red with a blue checker {best defence) if random (hard-play-easy) = 0[ ; changes the availability of the next 14 lines of code if (first column1) != 0[ set redlist fput (first column1) redlist redcheck set redlist remove-item 0 redlist] if (first column2) != 0[ set redlist fput (first column2) redlist redcheck set redlist remove-item 0 redlist] if (first column3) != 0[ set redlist fput (first column3) redlist redcheck set redlist remove-item 0 redlist] if (first column4) != 0[ set redlist fput (first column4) redlist redcheck set redlist remove-item 0 redlist] if (first column5) != 0[ set redlist fput (first column5) redlist redcheck set redlist remove-item 0 redlist] if (first column6) != 0[ set redlist fput (first column6) redlist redcheck set redlist remove-item 0 redlist] if (first column7) != 0[ set redlist fput (first column7) redlist redcheck set redlist remove-item 0 redlist]] ifelse pred = true [consplay][ ]] consplay] ]] end to consplay ifelse remainder (moves + 2) 2 = 0[stop][ ; CONNIE must wait her turn ifelse moves = 1[ifelse (p = 4) = true[ ; a set play for move 1 add-piece 1][add-piece 0] ; " " " " " " if view-brain = true[print " a set play "]][ ; " " " " " " ifelse pblue = true or pred = true[add-piece con-h][ ; CONNIE adds a checker in play add-piece -3 + random 7 if view-brain = true[ ; random if CONNIE has no better play print " p="+ p +" random-play "]]]] ; prints data for view-brain flag ; " " " " " set pblue false set pred false ; resets conquer and conquest end to conquer ; finds the 'p' number for CONNIE from blue-check set p item 0 bluelist set pblue true stop end to conquest ; finds the 'p' number for CONNIE from red-check set p item 0 redlist set pred true stop end to-report con-h ; transforms p to h and back to x ifelse remainder (p + 7) 7 = 0[set h 7][set h remainder (p + 7) 7] if h = 1 [report -3] if h = 2[report -2] if h = 3[report -1] if h = 4[report 0] if h = 5[report 1] if h = 6[report 2] if h = 7[report 3] end to flag ; prints some data for view-brain if view-brain = true and pblue = true[print " p="+ p +" a blue win"] if view-brain = true and pred = true[print " p="+ p +" stops a red 4"] end ; more brain below, but some of it is equivalent to the check-for-wins code in pre-CONNIE models. to swinb ; counts blue checkers in a line set winb winb + 1 end to swinr ; counts red checkers in a line set winr winr + 1 end to winsb ; detect a blue win and in-line conditions for set n n + 1 ; CONNIE's 'conquer' reporter of bluecheck ifelse winb = 4[ ifelse CONNIE = true[ if n >= 1 and n <= 69[if view-brain = true and pblue = true[ print " n="+ n +" a blue 4"] ; prints data for view-brain ifelse block = false[conquer set winb 0][won]]][won]][ set winb 0] end to winsr ; detect a red win and in-line conditions set n n + 1 ; CONNIE's 'conquest' reporter of redcheck ifelse winr = 4[ ifelse CONNIE = true[ if n >= 70 and n <= 138[if view-brain = true[ print " n="+ n +" just in time"] ; prints data for view-brain ifelse block = false[conquest set winr 0][won]]][won]][ set winr 0] end to won set winner? true print " " + current-player + " won the game in " + moves + " moves! " set moves 0 set winb 0 set winr 0 set next-player? "PLAYER-1" stop end ;The 'P' diagram 36 37 38 39 40 41 42 ; 29 30 31 32 33 34 35 ; 22 23 24 25 26 27 28 ; 15 16 17 18 19 20 21 ; 08 09 10 11 12 13 14 ; 01 02 03 04 05 06 07 to bluecheck set n 0 foreach[01 08 15 22][if member? ? bluelist = true[swinb]]winsb ; n = 1 up/down foreach[08 15 22 29][if member? ? bluelist = true[swinb]]winsb foreach[15 22 29 36][if member? ? bluelist = true[swinb]]winsb foreach[02 09 16 23][if member? ? bluelist = true[swinb]]winsb foreach[09 16 23 30][if member? ? bluelist = true[swinb]]winsb ; n = 5 foreach[16 23 30 37][if member? ? bluelist = true[swinb]]winsb foreach[03 10 17 24][if member? ? bluelist = true[swinb]]winsb foreach[10 17 24 31][if member? ? bluelist = true[swinb]]winsb foreach[17 24 31 38][if member? ? bluelist = true[swinb]]winsb foreach[04 11 18 25][if member? ? bluelist = true[swinb]]winsb ; n = 10 foreach[11 18 25 32][if member? ? bluelist = true[swinb]]winsb foreach[18 25 32 39][if member? ? bluelist = true[swinb]]winsb foreach[05 12 19 26][if member? ? bluelist = true[swinb]]winsb foreach[12 19 26 33][if member? ? bluelist = true[swinb]]winsb foreach[19 26 33 40][if member? ? bluelist = true[swinb]]winsb ; n = 15 foreach[06 13 20 27][if member? ? bluelist = true[swinb]]winsb foreach[13 20 27 34][if member? ? bluelist = true[swinb]]winsb foreach[20 27 34 41][if member? ? bluelist = true[swinb]]winsb foreach[07 14 21 28][if member? ? bluelist = true[swinb]]winsb foreach[14 21 28 35][if member? ? bluelist = true[swinb]]winsb ; n = 20 foreach[21 28 35 42][if member? ? bluelist = true[swinb]]winsb foreach[01 02 03 04][if member? ? bluelist = true[swinb]]winsb ; across foreach[02 03 04 05][if member? ? bluelist = true[swinb]]winsb foreach[03 04 05 06][if member? ? bluelist = true[swinb]]winsb foreach[04 05 06 07][if member? ? bluelist = true[swinb]]winsb ; n = 25 foreach[08 09 10 11][if member? ? bluelist = true[swinb]]winsb foreach[09 10 11 12][if member? ? bluelist = true[swinb]]winsb foreach[10 11 12 13][if member? ? bluelist = true[swinb]]winsb foreach[11 12 13 14][if member? ? bluelist = true[swinb]]winsb foreach[15 16 17 18][if member? ? bluelist = true[swinb]]winsb ; n = 30 foreach[16 17 18 19][if member? ? bluelist = true[swinb]]winsb foreach[17 18 19 20][if member? ? bluelist = true[swinb]]winsb foreach[18 19 20 21][if member? ? bluelist = true[swinb]]winsb foreach[22 23 24 25][if member? ? bluelist = true[swinb]]winsb foreach[23 24 25 26][if member? ? bluelist = true[swinb]]winsb ; n = 35 foreach[24 25 26 27][if member? ? bluelist = true[swinb]]winsb foreach[25 26 27 28][if member? ? bluelist = true[swinb]]winsb foreach[29 30 31 32][if member? ? bluelist = true[swinb]]winsb foreach[30 31 32 33][if member? ? bluelist = true[swinb]]winsb foreach[31 32 33 34][if member? ? bluelist = true[swinb]]winsb ; n = 40 foreach[32 33 34 35][if member? ? bluelist = true[swinb]]winsb foreach[36 37 38 39][if member? ? bluelist = true[swinb]]winsb foreach[37 38 39 40][if member? ? bluelist = true[swinb]]winsb foreach[38 39 40 41][if member? ? bluelist = true[swinb]]winsb foreach[39 40 41 42][if member? ? bluelist = true[swinb]]winsb ; n = 45 foreach[21 27 33 39][if member? ? bluelist = true[swinb]]winsb ; bk/diagonal foreach[14 20 26 32][if member? ? bluelist = true[swinb]]winsb foreach[20 26 32 38][if member? ? bluelist = true[swinb]]winsb foreach[07 13 19 25][if member? ? bluelist = true[swinb]]winsb foreach[13 19 25 31][if member? ? bluelist = true[swinb]]winsb ; n = 50 foreach[19 25 31 37][if member? ? bluelist = true[swinb]]winsb foreach[06 12 18 24][if member? ? bluelist = true[swinb]]winsb foreach[12 18 24 30][if member? ? bluelist = true[swinb]]winsb foreach[18 24 30 36][if member? ? bluelist = true[swinb]]winsb foreach[05 11 17 23][if member? ? bluelist = true[swinb]]winsb ; n = 55 foreach[11 17 23 29][if member? ? bluelist = true[swinb]]winsb foreach[04 10 16 22][if member? ? bluelist = true[swinb]]winsb foreach[15 23 31 39][if member? ? bluelist = true[swinb]]winsb ; fd/diagonal foreach[08 16 24 32][if member? ? bluelist = true[swinb]]winsb foreach[16 24 32 40][if member? ? bluelist = true[swinb]]winsb ; n = 60 foreach[01 09 17 25][if member? ? bluelist = true[swinb]]winsb foreach[09 17 25 33][if member? ? bluelist = true[swinb]]winsb foreach[17 25 33 41][if member? ? bluelist = true[swinb]]winsb foreach[02 10 18 26][if member? ? bluelist = true[swinb]]winsb foreach[10 18 26 34][if member? ? bluelist = true[swinb]]winsb ; n = 65 foreach[18 26 34 42][if member? ? bluelist = true[swinb]]winsb foreach[03 11 19 27][if member? ? bluelist = true[swinb]]winsb foreach[11 19 27 35][if member? ? bluelist = true[swinb]]winsb foreach[04 12 20 28][if member? ? bluelist = true[swinb]]winsb ; n = 69 end to redcheck set n 69 foreach[01 08 15 22][if member? ? redlist = true[swinr]]winsr ; n = 70 up/down foreach[08 15 22 29][if member? ? redlist = true[swinr]]winsr foreach[15 22 29 36][if member? ? redlist = true[swinr]]winsr foreach[02 09 16 23][if member? ? redlist = true[swinr]]winsr foreach[09 16 23 30][if member? ? redlist = true[swinr]]winsr foreach[16 23 30 37][if member? ? redlist = true[swinr]]winsr ; n = 75 foreach[03 10 17 24][if member? ? redlist = true[swinr]]winsr foreach[10 17 24 31][if member? ? redlist = true[swinr]]winsr foreach[17 24 31 38][if member? ? redlist = true[swinr]]winsr foreach[04 11 18 25][if member? ? redlist = true[swinr]]winsr foreach[11 18 25 32][if member? ? redlist = true[swinr]]winsr ; n = 80 foreach[18 25 32 39][if member? ? redlist = true[swinr]]winsr foreach[05 12 19 26][if member? ? redlist = true[swinr]]winsr foreach[12 19 26 33][if member? ? redlist = true[swinr]]winsr foreach[19 26 33 40][if member? ? redlist = true[swinr]]winsr foreach[06 13 20 27][if member? ? redlist = true[swinr]]winsr ; n = 85 foreach[13 20 27 34][if member? ? redlist = true[swinr]]winsr foreach[20 27 34 41][if member? ? redlist = true[swinr]]winsr foreach[07 14 21 28][if member? ? redlist = true[swinr]]winsr foreach[14 21 28 35][if member? ? redlist = true[swinr]]winsr foreach[21 28 35 42][if member? ? redlist = true[swinr]]winsr ; n = 90 foreach[01 02 03 04][if member? ? redlist = true[swinr]]winsr ; across foreach[02 03 04 05][if member? ? redlist = true[swinr]]winsr foreach[03 04 05 06][if member? ? redlist = true[swinr]]winsr foreach[04 05 06 07][if member? ? redlist = true[swinr]]winsr foreach[08 09 10 11][if member? ? redlist = true[swinr]]winsr ; n = 95 foreach[09 10 11 12][if member? ? redlist = true[swinr]]winsr foreach[10 11 12 13][if member? ? redlist = true[swinr]]winsr foreach[11 12 13 14][if member? ? redlist = true[swinr]]winsr foreach[15 16 17 18][if member? ? redlist = true[swinr]]winsr foreach[16 17 18 19][if member? ? redlist = true[swinr]]winsr ; n = 100 foreach[17 18 19 20][if member? ? redlist = true[swinr]]winsr foreach[18 19 20 21][if member? ? redlist = true[swinr]]winsr foreach[22 23 24 25][if member? ? redlist = true[swinr]]winsr foreach[23 24 25 26][if member? ? redlist = true[swinr]]winsr foreach[24 25 26 27][if member? ? redlist = true[swinr]]winsr ; n = 105 foreach[25 26 27 28][if member? ? redlist = true[swinr]]winsr foreach[29 30 31 32][if member? ? redlist = true[swinr]]winsr foreach[30 31 32 33][if member? ? redlist = true[swinr]]winsr foreach[31 32 33 34][if member? ? redlist = true[swinr]]winsr foreach[32 33 34 35][if member? ? redlist = true[swinr]]winsr ; n = 110 foreach[36 37 38 39][if member? ? redlist = true[swinr]]winsr foreach[37 38 39 40][if member? ? redlist = true[swinr]]winsr foreach[38 39 40 41][if member? ? redlist = true[swinr]]winsr foreach[39 40 41 42][if member? ? redlist = true[swinr]]winsr foreach[21 27 33 39][if member? ? redlist = true[swinr]]winsr ; n =115 bk/diagonal foreach[14 20 26 32][if member? ? redlist = true[swinr]]winsr foreach[20 26 32 38][if member? ? redlist = true[swinr]]winsr foreach[07 13 19 25][if member? ? redlist = true[swinr]]winsr foreach[13 19 25 31][if member? ? redlist = true[swinr]]winsr foreach[19 25 31 37][if member? ? redlist = true[swinr]]winsr ; n = 120 foreach[06 12 18 24][if member? ? redlist = true[swinr]]winsr foreach[12 18 24 30][if member? ? redlist = true[swinr]]winsr foreach[18 24 30 36][if member? ? redlist = true[swinr]]winsr foreach[05 11 17 23][if member? ? redlist = true[swinr]]winsr foreach[11 17 23 29][if member? ? redlist = true[swinr]]winsr ; n = 125 foreach[04 10 16 22][if member? ? redlist = true[swinr]]winsr foreach[15 23 31 39][if member? ? redlist = true[swinr]]winsr ; fd/diagonal foreach[08 16 24 32][if member? ? redlist = true[swinr]]winsr foreach[16 24 32 40][if member? ? redlist = true[swinr]]winsr foreach[01 09 17 25][if member? ? redlist = true[swinr]]winsr ; n = 130 foreach[09 17 25 33][if member? ? redlist = true[swinr]]winsr foreach[17 25 33 41][if member? ? redlist = true[swinr]]winsr foreach[02 10 18 26][if member? ? redlist = true[swinr]]winsr foreach[10 18 26 34][if member? ? redlist = true[swinr]]winsr foreach[18 26 34 42][if member? ? redlist = true[swinr]]winsr ; n = 135 foreach[03 11 19 27][if member? ? redlist = true[swinr]]winsr foreach[11 19 27 35][if member? ? redlist = true[swinr]]winsr foreach[04 12 20 28][if member? ? redlist = true[swinr]]winsr ; n = 138 end @#$#@#$#@ GRAPHICS-WINDOW 366 10 775 440 3 3 57.0 1 10 1 1 1 CC-WINDOW 9 278 357 441 Command Center BUTTON 374 391 429 424 1 wait 0.3 \nadd-piece -3 NIL 1 T OBSERVER T BUTTON 430 391 485 424 2 wait 0.3\nadd-piece -2 NIL 1 T OBSERVER T BUTTON 486 390 541 423 3 wait 0.3\nadd-piece -1 NIL 1 T OBSERVER T BUTTON 543 390 598 423 4 wait 0.3\nadd-piece 0 NIL 1 T OBSERVER T BUTTON 600 389 655 422 5 wait 0.3\nadd-piece 1 NIL 1 T OBSERVER T BUTTON 657 389 712 422 6 wait 0.3\nadd-piece 2 NIL 1 T OBSERVER T BUTTON 714 389 769 422 7 wait 0.3\nadd-piece 3 NIL 1 T OBSERVER T BUTTON 249 63 359 96 START PLAY setup NIL 1 T OBSERVER T TEXTBOX 25 164 219 246 PLAYER-1 always goes first and\ncan play against CONNIE by switching CONNIE to ON.\nPLAYER-2 can get CONNIE's help by switching her ON for a while. TEXTBOX 250 99 359 148 PLAYER-1 is RED\nPLAYER-2 and\nCONNIE are BLUE. TEXTBOX 23 11 212 164 CONNECT FOUR Click buttons\n1 to 7 to get checkers in line on a row, column or diagonal.\n4 in line is a win\n5 in line gives 2 wins \n6 in line gives 3 wins\n7 in line gives 4 wins \nALWAYS click START PLAY to \nstart or restart a game. MONITOR 217 10 360 59 NEXT PLAYER next-player? 0 1 MONITOR 179 63 243 112 next move moves + 1 0 1 SWITCH 252 197 360 230 view-brain view-brain 0 1 -1000 TEXTBOX 24 243 227 277 !!!! view-brain slows CONNIE !!!! p = patch number n = line number \n SWITCH 251 155 360 188 CONNIE CONNIE 0 1 -1000 SLIDER 251 239 361 272 hard-play-easy hard-play-easy 0 2 0 1 1 NIL @#$#@#$#@ WHAT IS IT? ----------- This model is a Netlogo version of the classic Milton Bradley/Hasbro game "Connect Four: The Vertical Four-in-a-Row Checkers Game." It is intended to be a two-player game, and is entirely for fun! The rules are simple. Each player places a colored-checker in one of the seven slots. The first player to get four in a row, column, or on a diagonal wins. HOW IT WORKS ------------ SETUP creates the game board, with seven columns and six rows. The grey space at the top of the screen is necessary because Netlogo's graphic canvas won't permit the exact dimensions of the game space. The white "holes" are turtles that serve as place-holders for the colored checkers. They have no other function in the game. ADD-PIECE [x] is called by the seven buttons on the bottom of the screen. They are used by the players to add each checker to the board. ADD-PIECE [x] finds the first "empty" space in the relevant column, and inserts a checker of the player's color. This procedure uses a list to evaluate possible y coordinates to find the first empty space in a column. Once placed on the board, the new turtle sets its color to that of the player, and uses SET-POSSIBLE-HEADINGS to set its own list of possible headings for evaluating each move. CHECK-FOR-WINNER is only run after seven moves have been completed. This procedure uses the two lists (single-headings and double-headings) to look in each of the legal directions to determine if the most recently-played checker has won the game. The procedure looks first to see if the latest piece is at the end of a chain of 4 like-checkers (single-headings), and then looks to see if it is inside (not on the end) of a string of four checkers. This analysis involves looking forward two checkers on a heading, and then "turning around" (by adding 180 degrees to the heading) to look at the two checkers in the opposite direction. When the game is over, the command window prints which side won, and in how many steps. To play again, either use the "PLAY AGAIN?" button (calling SETUP), or hit any one of the seven button on the bottom of the screen. HOW TO USE IT ------------- It's pretty self-explanatory. Find a friend, and start seeing who can win the game first. Its the 1970's version of outwit, outlast, and outplay! THINGS TO NOTICE ---------------- The code for this model is remarkably short, with just three meaningful procedures. (STARTUP loads the model but isn't necessary). Notice how the ADD-PIECES and CHECK-FOR-WINNERS procedures enable the game to work. That is the heart of the model. The game will only run under Netlogo 2.0 and later because of its reliance on the "ask patch-at-heading-and-distance" primitive. The model is not really "agent-based" in the traditional sense of the word, but it illustrates the robustness of the Netlogo environment and its ease of use. And it is just plain fun to play! EXTENDING THE MODEL ------------------- One possible extension would be to build a procedure that would provide a "Help" mode - either pointing out existing patterns of three like-checkers or warning when a player is "in check." Another extension would be to have the checkers appear at the top of the screen, and then "drop" into place in each column. A one-player version of the game (with a computer opponent) is probably the most challenging extension to the model, and would certainly take longer than the initial model to code, but it would be an amazing accomplishment! RELATED MODELS -------------- This model is related to the game models in the Netlogo Models Library. Unlike Frogger and Pac-Man, which require the awkward use of buttons to replicate the original joysticks, CONNECT FOUR plays completely like the original - with the one exception of having the ability to make all the checkers drop to the table. CREDITS AND REFERENCES ---------------------- This model was inspired by the Hasbro game "CONNECT FOUR" and is dedicated to Nicholas Gizzi, an enthusiastic six year-old who is fascinated by the original Connect Four, and is now learning to move virtual turtles around a computer screen! He dutifully beta-tested this model. The model was created by Michael C. Gizzi with assistance from Boyce Baker and Richard Vail. The model is copyright 2003 by the Center for Agent-Based Modeling, Mesa State College, 2508 Blichman Avenue, Grand Junction, CO 81505. http://www.modelingcomplexity.org. The original board game CONNECT FOUR is copyright Hasbro 1998. THE MODEL IS INTENDED SOLELY FOR EDUCATIONAL AND ENTERTAINMENT PURPOSES. IT MAY NOT BE REPRODUCED FOR COMMERCIAL USE WITHOUT VIOLATING EITHER OF THE COPYRIGHTS LISTED HERE. NOTES ON connect4 and CONNIE -------------------------- This model was extended and changed as a compliment to Michael for his original work in giving us connect4, which is on the Netlogo Community Models site. Also it was to respond to his suggestion that "A one-player version of the game (with a computer opponent) is probably the most challenging extension to the model". HOW RIGHT HE WAS!!! I have added a different CHECK-FOR-WINNER procedure; also CONNIE who plays a fair game, adjustable between 'hard' and 'easy', for those who like to play against a machine. CONNIE exhibits no intelligence, in fact a large proportion of her play is random because this avoids some of the repetition of machine play. Also it was discovered that the spatial relations of the game demand very complicated procedures to provide a greater level of play. The prime reason for this is the ease with which twofold, threefold, etc lines of 3 with common members can be formed and the extreme difficulty of anticipating the formation. The Procedures section includes detailed explanations of the code and some of its working can be viewed in the Command Center. Derek Rush who can be contacted on derekrush@beeb.net February 2004. @#$#@#$#@ default true 0 Polygon -7566196 true true 150 5 40 250 150 205 260 250 ant true 0 Polygon -7566196 true true 136 61 129 46 144 30 119 45 124 60 114 82 97 37 132 10 93 36 111 84 127 105 172 105 189 84 208 35 171 11 202 35 204 37 186 82 177 60 180 44 159 32 170 44 165 60 Polygon -7566196 true true 150 95 135 103 139 117 125 149 137 180 135 196 150 204 166 195 161 180 174 150 158 116 164 102 Polygon -7566196 true true 149 186 128 197 114 232 134 270 149 282 166 270 185 232 171 195 149 186 149 186 Polygon -7566196 true true 225 66 230 107 159 122 161 127 234 111 236 106 Polygon -7566196 true true 78 58 99 116 139 123 137 128 95 119 Polygon -7566196 true true 48 103 90 147 129 147 130 151 86 151 Polygon -7566196 true true 65 224 92 171 134 160 135 164 95 175 Polygon -7566196 true true 235 222 210 170 163 162 161 166 208 174 Polygon -7566196 true true 249 107 211 147 168 147 168 150 213 150 arrow true 0 Polygon 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