[3] **viXra:1207.0064 [pdf]**
*submitted on 2012-07-17 02:27:13*

**Authors:** Pierre-Yves Gaillard

**Comments:** 1 Page.

We give a short proof of Zorn's Lemma.

**Category:** Set Theory and Logic

[2] **viXra:1207.0039 [pdf]**
*submitted on 2012-07-11 06:01:20*

**Authors:** Pierre-Yves Gaillard

**Comments:** 2 Pages.

The book "Categories and Sheaves" by Kashiwara and Schapira starts with a few statements which are not proved, a reference being given instead. We spell out the proofs in a short and self-contained way.

**Category:** Set Theory and Logic

[1] **viXra:1207.0009 [pdf]**
*replaced on 2012-07-09 00:35:18*

**Authors:** Pierre-Yves Gaillard

**Comments:** 3 Pages.

We unsuccessfully try to give definitions in the spirit of Bourbaki's set theory for the basic notions of category theory. The goal is to avoid using either Grothendieck's universes axiom, or "classes" (or "collections") of sets which are not sets. We explain why our attempt fails.

**Category:** Set Theory and Logic