Name Rascal/Libraries/Prelude/ListRelation/complement

Synopsis Complement of a list relation.

Function

1. lrel[&T0, &T1] complement(lrel[&T0, &T1] R)
2. lrel[&T0, &T1, &T2] complement(lrel[&T0, &T1, &T2] R)
3. lrel[&T0, &T1, &T2, &T3] complement(lrel[&T0, &T1, &T2, &T3] R)
4. lrel[&T0, &T1, &T2, &T3, &T4] complement(lrel[&T0, &T1, &T2, &T3, &T4] R)

Usage import ListRelation;

Description Given a list relation R a new relation U can be constructed that contains all possible tuples with element values that occur at corresponding tuple positions in R. The function complement returns the complement of R relative to U, in other words: U - R.

Examples

rascal>import ListRelation;
ok

Declare R and compute corresponding U:

rascal>R = [<1,10>, <2, 20>, <3, 30>];
lrel[int,int]: [
  <1,10>,
  <2,20>,
  <3,30>
]
rascal>U = domain(R) * range(R);
lrel[int,int]: [
  <1,10>,
  <1,20>,
  <1,30>,
  <2,10>,
  <2,20>,
  <2,30>,
  <3,10>,
  <3,20>,
  <3,30>
]

Here is the complement of R computed in two ways:

rascal>U - R;
lrel[int,int]: [
  <1,20>,
  <1,30>,
  <2,10>,
  <2,30>,
  <3,10>,
  <3,20>
]
rascal>complement([<1,10>, <2, 20>, <3, 30>]);
lrel[int,int]: [
  <1,20>,
  <1,30>,
  <2,10>,
  <2,30>,
  <3,10>,
  <3,20>
]

Questions

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