



 
Hi, I started a chain as Claude described starting with [0,1]. My chain was [0,1][1,3][3,4][4,5][5,6][6,0][0,0][0,2][2,1][1,4][4,0][0,5][ 5,3][3,0] I could continue as Claude describes to use the 28 dominos and my list and his are different. I am sure of this since in his list [0,4] is between [0,3] and [0,5] and in my list it is not. Penny We got a response
I am going to label four of the dominos, $A$ is [01], $B$ is [0,3], $C$ is [[04], and $D$ is [05]. If you complete Claude's solution and place the dominos clockwise on a circle then you get with the remaining dominos in the appropriate positions. Notice that if you start at $A$ and go around the circle either clockwise or counterclockwise, $C$ is between $B$ and $D.$ If you complete my solution and place the dominos clockwise on a circle then you get In this configuration if you start at $A$ and go around the circle either clockwise or counterclockwise, $C$ is not between $B$ and $D.$Hence the two solutions are different. Penny 



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