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Posets :: moebiusFunction(Poset)

moebiusFunction(Poset) -- returns the Moebius function values for the unique minimal element to each element of the poset

Synopsis

Description

This routine returns the Moebius function values for the unique minimal element to each element of the poset. If P has more than one minimal element, an error will be signalled. In this example, a is the minimal element of P; M lists the Moebius function values from a to each element of P.
i1 : P = poset ({a,b,c,d},{(a,b), (b,c), (b,d)})

o1 = Poset{cache => CacheTable{}                }
           GroundSet => {a, b, c, d}
           RelationMatrix => | 1 1 1 1 |
                             | 0 1 1 1 |
                             | 0 0 1 0 |
                             | 0 0 0 1 |
           Relations => {(a, b), (b, c), (b, d)}

o1 : Poset
i2 : M = moebiusFunction(P)

o2 = HashTable{a => 1 }
               b => -1
               c => 0
               d => 0

o2 : HashTable

See also