Combinatorics was introduced by Ramsey to solve a special case of the decision problem for the first-order predicate calculus.
According to it, sky blue would be the blue of the first order in Newton's scale.
The light scattered from small particles is of a much richer blue than the blue of the first order as reflected from a very thin plate.
He was a master printer and an artist of the first order.
For a single quantic of the first order (ab) is the symbol of a function of the coefficients which vanishes identically; thus (ab) =a1b2-a2bl= aw l -a1ao=0 and, indeed, from a remark made above we see that (ab) remains unchanged by interchange of a and b; but (ab), = -(ba), and these two facts necessitate (ab) = o.
