`HasseDiagram( `

`rel` )

`HasseDiagram`

returns the Hasse diagram of the binary relation `rel` if
this is a partial order. It will signal an error if `rel` is not a
partial order (see IsPartialOrder).

gap> HasseDiagram( Relation( [ [ 1 ], [ 1, 2 ], [ 1, 2, 3 ] ] ) ); Relation( [ [ ], [ 1 ], [ 2 ] ] )

The **Hasse diagram** of a partial order *R subseteq {1, ..., n}
x {1, ..., n}* is the smallest relation *H subseteq {1, ...,
n} x {1, ..., n}* such that *R* is the reflexive and transitive
closure of *H*.