tractatus.13

・frege and Russell:
Number is an attribute of a set. For example, when we say "there's 10 apples", the number 10 is an attribute of the set 'apple'.
Or, number is a set composed of sets members is same number. For instance, 10 is an enormous set composed of sets. and all these sets' members are 10 each.
・wittgenstein:
Number is the number of algorithm(???). Number is the number(frequency) of operation. Hense, it is not a name any more than the logic operator is. (it is no more a name than the logic operator is)
Therefore, '1+1=2' is not a tautology as logical empiricists say. The reason is that number is not a name. Thus, '1+1=2' is not a proposition.