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joinExists -- determines if the join exists

Synopsis

Description

This function determines if least element that is greater than both a and b in P exists.
i1 : P = poset ({a,b,c,d,e}, {(a,d),(b,d),(b,e),(c,e)});
i2 : joinExists (P,d,e)

o2 = false
i3 : joinExists(P,a,b)

o3 = true

Caveat

If the join exists, to find it use posetJoin.

See also

Ways to use joinExists :