Sweezy's occ

[Forstater, Mathew]

The organic composition of capital (occ) is usually defined as c/v.  With this definition, it is easy to show that the value rate of profit, s/(c+v), depends on the rate of surplus value, s/v, and the occ, because s/(c+v) = (s/v)/[(c/v) + 1].   Why does Sweezy define the occ as c/(c+v) in The Theory of Capitalist Development?  This then leads him to a more complicated proof to show that s/(c+v) = s’ (1 - q), where s’ is the rate of surplus value and q is the occ by his definition, = c/(c+v).   Thanks, mat