Strategy in Coloring a 4x4 empty grid and the one who completes any 2x2 area of the grid is the loser

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Alice and Bob are playing the following game: They have a 4x4 empty grid and take turns coloring one square each, starting with Alice. Assume that both players will colour the squares in with the same colour. Whoever completes any $2times2$ area on the grid after having made their move, is the loser.



Is there any winning strategy for either of the two players?







share|improve this question






















  • This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
    – El-Guest
    Aug 16 at 14:52







  • 3




    The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
    – Peter Taylor
    Aug 16 at 17:37






  • 2




    You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
    – Riley
    Aug 16 at 23:22














up vote
1
down vote

favorite












Alice and Bob are playing the following game: They have a 4x4 empty grid and take turns coloring one square each, starting with Alice. Assume that both players will colour the squares in with the same colour. Whoever completes any $2times2$ area on the grid after having made their move, is the loser.



Is there any winning strategy for either of the two players?







share|improve this question






















  • This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
    – El-Guest
    Aug 16 at 14:52







  • 3




    The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
    – Peter Taylor
    Aug 16 at 17:37






  • 2




    You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
    – Riley
    Aug 16 at 23:22












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Alice and Bob are playing the following game: They have a 4x4 empty grid and take turns coloring one square each, starting with Alice. Assume that both players will colour the squares in with the same colour. Whoever completes any $2times2$ area on the grid after having made their move, is the loser.



Is there any winning strategy for either of the two players?







share|improve this question














Alice and Bob are playing the following game: They have a 4x4 empty grid and take turns coloring one square each, starting with Alice. Assume that both players will colour the squares in with the same colour. Whoever completes any $2times2$ area on the grid after having made their move, is the loser.



Is there any winning strategy for either of the two players?









share|improve this question













share|improve this question




share|improve this question








edited Aug 16 at 14:50









El-Guest

8,2551548




8,2551548










asked Aug 16 at 13:48









philip

507




507











  • This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
    – El-Guest
    Aug 16 at 14:52







  • 3




    The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
    – Peter Taylor
    Aug 16 at 17:37






  • 2




    You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
    – Riley
    Aug 16 at 23:22
















  • This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
    – El-Guest
    Aug 16 at 14:52







  • 3




    The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
    – Peter Taylor
    Aug 16 at 17:37






  • 2




    You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
    – Riley
    Aug 16 at 23:22















This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
– El-Guest
Aug 16 at 14:52





This was flagged as off-topic; however I think adding the above clarity will resolve this issue. I have therefore edited the question per @philip's comments below to reflect that he intended both players to colour in squares with the same colour.
– El-Guest
Aug 16 at 14:52





3




3




The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
– Peter Taylor
Aug 16 at 17:37




The same question was posted on a different stack by (apparently) a different user one hour earlier: math.stackexchange.com/q/2884764/5676
– Peter Taylor
Aug 16 at 17:37




2




2




You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
– Riley
Aug 16 at 23:22




You also posted the answer seen on the math.se question here. I pointed out a mistake, then you posted that exact same comment on the math.se answer, then deleted your answer here. That makes three things you've plagiarized so far.
– Riley
Aug 16 at 23:22










2 Answers
2






active

oldest

votes

















up vote
7
down vote













First of all, I'm assuming that Bob and Alice are painting with different colors and that we are only concerned with a $2times 2$ square of the same color. Now I realize that I may have interpreted the problem incorrectly.




Bob




can always force a win or draw with the following strategy:




Whatever square Alice colors, Bob should color the square symmetric with respect to the origin (rotate 180 degrees). This way, Bob can never complete a $2times 2$ square unless Alice has just completed a rotated version of that square. In fact, Bob can win/draw this way on any $2ntimes 2n$ grid.







share|improve this answer






















  • this is a draw, not a win
    – JonMark Perry
    Aug 16 at 14:02










  • This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
    – PotatoLatte
    Aug 16 at 14:04










  • @PotatoLatte; so they use the same colour then?
    – JonMark Perry
    Aug 16 at 14:06











  • I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
    – Riley
    Aug 16 at 14:09










  • Well I didn't write the problem; So this may be right
    – PotatoLatte
    Aug 16 at 14:11

















up vote
3
down vote













Bob wins if




both Alice and Bob only colour the edges. Then Alice is eventually forced to play in the middle.




If Alice colours an inner cell for the first time:




Bob colours the diagonally opposite, and reverts to the edge strategy ignoring the extremal corners of the extremal sub-grids with inner cells. We either end up with a saturated grid (Bob wins), or Alice colours one, and so Bob colours the opposite corner with the same effect.




Alice colours a second inner cell:




Bob colours the opposite extremal corner, and the same strategy gives Bob the win.




Summary:




Bob always wins.







share|improve this answer




















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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    7
    down vote













    First of all, I'm assuming that Bob and Alice are painting with different colors and that we are only concerned with a $2times 2$ square of the same color. Now I realize that I may have interpreted the problem incorrectly.




    Bob




    can always force a win or draw with the following strategy:




    Whatever square Alice colors, Bob should color the square symmetric with respect to the origin (rotate 180 degrees). This way, Bob can never complete a $2times 2$ square unless Alice has just completed a rotated version of that square. In fact, Bob can win/draw this way on any $2ntimes 2n$ grid.







    share|improve this answer






















    • this is a draw, not a win
      – JonMark Perry
      Aug 16 at 14:02










    • This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
      – PotatoLatte
      Aug 16 at 14:04










    • @PotatoLatte; so they use the same colour then?
      – JonMark Perry
      Aug 16 at 14:06











    • I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
      – Riley
      Aug 16 at 14:09










    • Well I didn't write the problem; So this may be right
      – PotatoLatte
      Aug 16 at 14:11














    up vote
    7
    down vote













    First of all, I'm assuming that Bob and Alice are painting with different colors and that we are only concerned with a $2times 2$ square of the same color. Now I realize that I may have interpreted the problem incorrectly.




    Bob




    can always force a win or draw with the following strategy:




    Whatever square Alice colors, Bob should color the square symmetric with respect to the origin (rotate 180 degrees). This way, Bob can never complete a $2times 2$ square unless Alice has just completed a rotated version of that square. In fact, Bob can win/draw this way on any $2ntimes 2n$ grid.







    share|improve this answer






















    • this is a draw, not a win
      – JonMark Perry
      Aug 16 at 14:02










    • This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
      – PotatoLatte
      Aug 16 at 14:04










    • @PotatoLatte; so they use the same colour then?
      – JonMark Perry
      Aug 16 at 14:06











    • I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
      – Riley
      Aug 16 at 14:09










    • Well I didn't write the problem; So this may be right
      – PotatoLatte
      Aug 16 at 14:11












    up vote
    7
    down vote










    up vote
    7
    down vote









    First of all, I'm assuming that Bob and Alice are painting with different colors and that we are only concerned with a $2times 2$ square of the same color. Now I realize that I may have interpreted the problem incorrectly.




    Bob




    can always force a win or draw with the following strategy:




    Whatever square Alice colors, Bob should color the square symmetric with respect to the origin (rotate 180 degrees). This way, Bob can never complete a $2times 2$ square unless Alice has just completed a rotated version of that square. In fact, Bob can win/draw this way on any $2ntimes 2n$ grid.







    share|improve this answer














    First of all, I'm assuming that Bob and Alice are painting with different colors and that we are only concerned with a $2times 2$ square of the same color. Now I realize that I may have interpreted the problem incorrectly.




    Bob




    can always force a win or draw with the following strategy:




    Whatever square Alice colors, Bob should color the square symmetric with respect to the origin (rotate 180 degrees). This way, Bob can never complete a $2times 2$ square unless Alice has just completed a rotated version of that square. In fact, Bob can win/draw this way on any $2ntimes 2n$ grid.








    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Aug 16 at 14:14

























    answered Aug 16 at 13:54









    Riley

    10.4k43170




    10.4k43170











    • this is a draw, not a win
      – JonMark Perry
      Aug 16 at 14:02










    • This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
      – PotatoLatte
      Aug 16 at 14:04










    • @PotatoLatte; so they use the same colour then?
      – JonMark Perry
      Aug 16 at 14:06











    • I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
      – Riley
      Aug 16 at 14:09










    • Well I didn't write the problem; So this may be right
      – PotatoLatte
      Aug 16 at 14:11
















    • this is a draw, not a win
      – JonMark Perry
      Aug 16 at 14:02










    • This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
      – PotatoLatte
      Aug 16 at 14:04










    • @PotatoLatte; so they use the same colour then?
      – JonMark Perry
      Aug 16 at 14:06











    • I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
      – Riley
      Aug 16 at 14:09










    • Well I didn't write the problem; So this may be right
      – PotatoLatte
      Aug 16 at 14:11















    this is a draw, not a win
    – JonMark Perry
    Aug 16 at 14:02




    this is a draw, not a win
    – JonMark Perry
    Aug 16 at 14:02












    This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
    – PotatoLatte
    Aug 16 at 14:04




    This is wrong; What if Alice does the middle 2 squares of the second row? Then Bob would be the one to finish it
    – PotatoLatte
    Aug 16 at 14:04












    @PotatoLatte; so they use the same colour then?
    – JonMark Perry
    Aug 16 at 14:06





    @PotatoLatte; so they use the same colour then?
    – JonMark Perry
    Aug 16 at 14:06













    I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
    – Riley
    Aug 16 at 14:09




    I misunderstood the problem, assuming that Alice and Bob are painting with different colors, and we are only concerned with $2times 2$ squares of the same color.
    – Riley
    Aug 16 at 14:09












    Well I didn't write the problem; So this may be right
    – PotatoLatte
    Aug 16 at 14:11




    Well I didn't write the problem; So this may be right
    – PotatoLatte
    Aug 16 at 14:11










    up vote
    3
    down vote













    Bob wins if




    both Alice and Bob only colour the edges. Then Alice is eventually forced to play in the middle.




    If Alice colours an inner cell for the first time:




    Bob colours the diagonally opposite, and reverts to the edge strategy ignoring the extremal corners of the extremal sub-grids with inner cells. We either end up with a saturated grid (Bob wins), or Alice colours one, and so Bob colours the opposite corner with the same effect.




    Alice colours a second inner cell:




    Bob colours the opposite extremal corner, and the same strategy gives Bob the win.




    Summary:




    Bob always wins.







    share|improve this answer
























      up vote
      3
      down vote













      Bob wins if




      both Alice and Bob only colour the edges. Then Alice is eventually forced to play in the middle.




      If Alice colours an inner cell for the first time:




      Bob colours the diagonally opposite, and reverts to the edge strategy ignoring the extremal corners of the extremal sub-grids with inner cells. We either end up with a saturated grid (Bob wins), or Alice colours one, and so Bob colours the opposite corner with the same effect.




      Alice colours a second inner cell:




      Bob colours the opposite extremal corner, and the same strategy gives Bob the win.




      Summary:




      Bob always wins.







      share|improve this answer






















        up vote
        3
        down vote










        up vote
        3
        down vote









        Bob wins if




        both Alice and Bob only colour the edges. Then Alice is eventually forced to play in the middle.




        If Alice colours an inner cell for the first time:




        Bob colours the diagonally opposite, and reverts to the edge strategy ignoring the extremal corners of the extremal sub-grids with inner cells. We either end up with a saturated grid (Bob wins), or Alice colours one, and so Bob colours the opposite corner with the same effect.




        Alice colours a second inner cell:




        Bob colours the opposite extremal corner, and the same strategy gives Bob the win.




        Summary:




        Bob always wins.







        share|improve this answer












        Bob wins if




        both Alice and Bob only colour the edges. Then Alice is eventually forced to play in the middle.




        If Alice colours an inner cell for the first time:




        Bob colours the diagonally opposite, and reverts to the edge strategy ignoring the extremal corners of the extremal sub-grids with inner cells. We either end up with a saturated grid (Bob wins), or Alice colours one, and so Bob colours the opposite corner with the same effect.




        Alice colours a second inner cell:




        Bob colours the opposite extremal corner, and the same strategy gives Bob the win.




        Summary:




        Bob always wins.








        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Aug 16 at 14:43









        JonMark Perry

        13.3k42666




        13.3k42666



























             

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