We define P C-polynomial of graph which is related to clique, (in)dependence and matching polynomials. The growth rate of partially commutative monoid is equal to the largest root β(G) of P C-polynomial of the corresponding graph.The random algebra is defined in such way that its growth rate equals the largest root of P C-polynomial of random graph. We prove that for almost all graphs all sufficiently large real roots of P C-polynomial lie in neighbourhoods of roots of P Cpolynomial of random graph. We show how to calculate the series expansions of the latter roots. The average value of β(G) over all graphs with the same number of vertices is computed.We found the graphs on which the maximal value of β(G) with fixed numbers of vertices and edges is reached. From this, we derive the upper bound of β(G). Modulo one assumption, we do the same for minimal value of β(G).We study the Nordhaus Gaddum bounds of β(G) + β( Ḡ) and β(G)β( Ḡ).