problem with the derivation of the parameter q (p. 66)

[John Anderson]

Gee, I had to dredge up old memories:

The implicit assumption underlying Equation 3.15 is P(E|D,F) = 1 for all
E which is to say that if one keeps working at an unsolvable problem one
will eventually wind up expending any amount of effort E.  In contrast.

P(E1|S,D) < P(E2|S,D) if E1 > E2

which is to say that one eventually solves a solvable problem and stops
putting effort in.

In any case, since P(E|D,F) = 1, P(F,D,E) = P(F,D) and from that one can
substitute into Mayer's equations.