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• CommentRowNumber1.
• CommentAuthorTim Campion
• CommentTimeFeb 23rd 2021

Added a “warning” for something that tripped me up: the classifying topos of a classical first-order theory is typically not Boolean, even though the classifying pretopos is Boolean. For a topos to be Boolean is much stronger – as Blass and Scedrov showed, it implies $\aleph_0$-categoricity.