gaussianRing(...,lVariableName=>...) -- symbol used for indeterminates in a ring of Gaussian joint probability distributions

i1 : G = mixedGraph(digraph {{b,{c,d}},{c,{d}}},bigraph {{a,d}})

o1 = MixedGraph{Bigraph => Bigraph{a => {d}}   }
                                   d => {a}
                Digraph => Digraph{b => {c, d}}
                                   c => {d}
                                   d => {}
                Graph => Graph{}

o1 : MixedGraph

i2 : gens gaussianRing(G,lVariableName=>"lambda")

o2 = {lambda   , lambda   , lambda   , p   , p   , p   , p   , p   , s   ,
            b,c        b,d        c,d   a,a   b,b   c,c   d,d   a,d   a,a 
     ------------------------------------------------------------------------
     s   , s   , s   , s   , s   , s   , s   , s   , s   }
      a,b   a,c   a,d   b,b   b,c   b,d   c,c   c,d   d,d

o2 : List