[Sean1708]

> In fact they must converge

Are you sure? Is this board not a counter-example if A starts on the right-most column and B starts on the second from the right:

  x x x x x x x 8 9
  x x x x x x 8 x 9
  x x x x x 8 x x 9
  x x x x 7 x x x 9
  x x 7 x x x x x A
  B x x x x x x

[falsedan]

Yes, the claim is 'at least two of the paths taken from the 10 cards on the first row must converge', not 'there are no paths taken from the 10 cards on the first row which do not converge'.

[irishsultan]

I may have not made it clear, but like falsedan said, I'm not claiming that all paths must converge, only that at least two paths must converge.

edit: That being said, I made a mistake by following the claim from above that there are 10 possible paths, in fact there are only 9 cards in a row.

[sp332]

TFA says the two-deck version is successful about 95% of the time. If you click through, it says the one-deck version works 80% of the time.