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63 votes
4 answers
7k views

When size matters in category theory for the working mathematician

I think a related question might be this (Set-Theoretic Issues/Categories). There are many ways in which you can avoid set theoretical paradoxes in dealing with category theory (see for instance ...
5 votes
2 answers
629 views

Applications of ZFA-Set Theory

The set theory with atoms (ZFA), is a modified version of set theory, and is characterized by the fact that it admits objects other than sets, atoms. Atoms are objects which do not have any elements. ...
157 votes
5 answers
28k views

What makes dependent type theory more suitable than set theory for proof assistants?

In his talk, The Future of Mathematics, Dr. Kevin Buzzard states that Lean is the only existing proof assistant suitable for formalizing all of math. In the Q&A part of the talk (at 1:00:00) he ...
6 votes
1 answer
994 views

Which branches of mathematics can be done just in terms of morphisms and composition?

Consider the first-order language $L_{\omega\omega}$ of the signature $L:=\{\mathrm{dom}, \mathrm{cod}, \mathrm{comp}\}$, where $\mathrm{dom}$ and $\mathrm{cod}$ are unary function symbols and $\...
50 votes
4 answers
6k views

Do set-theorists use informal set theory as their meta-theory when talking about models of ZFC?

Here, Noah Schweber writes the following: Most mathematics is not done in ZFC. Most mathematics, in fact, isn't done axiomatically at all: rather, we simply use propositions which seem "intuitively ...
8 votes
1 answer
1k views

Does equality between sets contradict the philosophy behind structural set theory?

Zermelo-Fraenkel set theory (with choice) is commonly accepted as the standard foundation of mathematics. It is a material set theory. This means that for every two objects/sets $a,b$ one can ask ...
19 votes
2 answers
2k views

Which kind of foundation are mathematicians using when proving metatheorems?

Zermelo-Fraenkel set theory (with choice) is commonly accepted as the standard foundation of mathematics. It is a material set theory. For every two objects/sets $a,b$ one can ask whether $a=b$ or not....
1 vote
0 answers
223 views

What should one know about abstract sets and structural foundations?

Recently I came by accident across the book sets for mathematics by Lawvere. It says: First we deplete the object of nearly all content. We could think of an idealized computer memory bank that ...
0 votes
1 answer
678 views

Why do we try to encode every mathematical object as a set? [closed]

Probably everyone of us has seen set-theoretic encodings of mathematical objects which we wouldn't naturally consider to be sets. May it be the "definition" of a function from $A$ to $B$ as a relation ...
6 votes
2 answers
1k views

Why can't mathematics be formalised in terms of classes rather than sets? [closed]

I've always been curious about the seeming compulsion to found mathematics upon sets, be it ZF(C) or some other system. Of course, there are other approaches these days like category theory and type ...