It we use Roman letters for mere numbers, capitals for instants of time, Greek letters for time-steps, and a parenthesis to denote a couple, the laws assumed by Hamilton as the basis of a system were as follows: (B1, B 2) - (A i, A2) = (Bi - A,, B2A 2) = (a, 13); (a, b) (a, #)= (aa - b(3, ba--+a(3).2 To show how we give, by such assumptions, a real interpretation to the ordinary algebraic imaginary, take the simple case a=o, b= r, and the second of the above formulae gives (o, 1) (a, (3) = (- 1 3, a).
If the string begins with an open parenthesis, it is treated as a standard format string.
These are arrays indexed by token type and parenthesis level (0, 1 and 2+).