The function ` Relation::global_decls()`
returns a pointer to the
collection of ` Variable_ID`
s that contains all the uses of global
variables in the relation.
This collection may include some global variables that have been
eliminated during simplification.

The function `
Relation::query_difference(Variable_ID v1, Variable_ID v2,
int &lowerBound, int &upperBound,
bool &guaranteed)
`
can be used to determine bounds on the possible value of
` v1 - v2`
.
Note that these bounds are not necessarily tight.
After this call, ` guaranteed`
will be true if these bounds
are guaranteed to be tight.
If the difference is not bounded below, ` lowerBound`
will be
` negInfinity`
.
If the difference is not bounded above, ` upperBound`
will be
` posInfinity`
.
These constants are defined in ``` oc.h`
'', which is included by
``` omega.h`
''.

omega@cs.umd.edu