The program takes as {TAIL ~ input} {HEAD ~ an initial data set} that contains probabilistic information and returns as output a sequence of elementary operations  
The program takes as { TAIL ~ input } { HEAD ~ an initial data set } that contains probabilistic information and returns as output a sequence of elementary operations
OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH