The DTAC program uses depth-first search to find an unconditional claim in 
bridge; that is, a line of play that is guaranteed to succeed whatever 
the distribution of the outstanding cards among the defenders. It can also 
find claims that are guaranteed to succeed under specified assumptions 
about the distribution of the defenders. cards. Lastly, DTAC can find a 
claim which requires losing a trick at some point. Using transposition 
tables to detect repeated positions, DTAC can carry out a complete DFS to 
find an unconditional ordered claim in less than 0.001 seconds on average, 
and less than 1 second for claims which lose a trick. The source code for 
DTAC is available from: http://cs.nyu.edu/~pmb309/DTAC.html