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Posets :: joinExists

joinExists -- determines if the join exists for two elements of a poset



The join of $a$ and $b$ in $P$, if it exists, is the unique least element greater than both $a$ and $b$.

i1 : P = poset {{a,b}, {a,c}, {a,d}, {c,e}, {d,e}};
i2 : joinExists(P, b, c)

o2 = false
i3 : joinExists(P, c, d)

o3 = true
i4 : Q = poset {{a,b}, {a,c}, {b,d}, {c,d}, {b,e}, {c,e}};
i5 : joinExists(P, b, c)

o5 = false

See also

Ways to use joinExists :

For the programmer

The object joinExists is a method function.