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sources -- returns the sources of a digraph



A source of a Digraph D is a vertex of D that has no parents. That is, v is a source of D if and only if there are only edges pointing from v; none can be pointing into v (there is no edge of the form (v,u)).

i1 : D = digraph({a,b,c,d,e},{{a,b},{b,c},{b,d},{e,b}});
i2 : sources D

o2 = {a, e}

o2 : List

See also

Ways to use sources :

For the programmer

The object sources is a method function.