*DEP-FAILERS* performs a similar type of processing with regards to the DEP rules
of each rule. The aim is, for each rule A, to record all the other rules that must be
failed 
if that rule is instantiated. *DEPENDENCIES* records all of
the the constraints that would conflict with a given DEP rule. Each of these constraints
is simply looked up in *CON* to see if it exists, and if it does, where it would be
originated from. This originating node then is added to *DEP-FAILERS* for the
corresponding rule.
In this example, the DEP rules in RELATION-20 do not conflict with any effects found in the tree. In fact, there are really no good examples of *DEP-FAILERS* here. If, however, the second rule in CROSS-1 had a DEP precondition of check-con (NC (form loc)), then this precondition would conflict with the effects of both the rules in DEATH-1, since they both impose constraints on CROSS-1 that it must be (C (form loc)). This is the type of information that would be stored in *DEP-FAILERS*.