 ...variables,

Frege used the word `function' where we now use the word `relation'. This was again adopted by Hilbert and Ackermann in the second edition of their book (1938). Unfortunately we also use the words `function symbol' in modern logic, but with quite a different meaning, namely such will be interpreted as a function on a domain to itself.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
 ...geometry,

In a letter to Hilbert at a later date he said there was no reason to prove the axioms of geometry consistent because they were true.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
 ...False

Frege describes the truth value of 17#17 for each of the four possible truth values of P,Q. Thus we almost have the first
truth table;
but there is no table, just a verbal description.
Truth tables are usually attributed to Wittgenstein who was well versed in
Frege's work, and had gone to study with Russell at Frege's suggestion.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
 ...law
 In Frege's book it was written
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
 ...have
 A slight variation on this applies to 33#33, namely one gets 34#34.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.