4
votes
1answer
757 views

Bourbaki theory of isomorphism, examples of untransportable formulas

In their book "Theory of sets" Bourbaki suggested a general theory of isomorphism. (See also http://www.tau.ac.il/~corry/publications/articles/pdf/bourbaki-structures.pdf ) The example of an ...
6
votes
7answers
1k views

The isomorphism inference rule

Suppose we are writing very detailed proofs, absolutely without any gaps (for example, for checking proofs by computer). In such formal proofs every step (even a trivial one) must be justified. For ...
10
votes
3answers
3k views

Bourbaki's epsilon-calculus notation

Bourbaki used a very very strange notation for the epsilon-calculus consisting of $\tau$s and $\blacksquare$. In fact, that box should not be filled in, but for some reason, I can't produce a \Box. ...