`EmptyRelation( `

`n` )

`EmptyRelation`

returns the empty relation of degree. This is the
relation *{ } subseteq {1, ..., n} x {1, ..., n}*.

gap> EmptyRelation( 5 ) ; Relation( [ [ ], [ ], [ ], [ ], [ ] ] )

The empty relation of degree `n` acts as zero in the full relation monoid
of degree `n`.