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Per aspera ad astra.


1d
suggested suggested edit on Defining new symbols (abbreviations) in first-order logic
Aug
16
accepted A better way to define $\bigcap S$?
Aug
16
comment Can a set have a subset which doesn't exist?
@AsafKaragila: I didn't read your answer at that moment, but I put it aside to read it later (make a bookmark). So I would have read it anyway.
Aug
16
comment Can a set have a subset which doesn't exist?
I don't have enough background to fully understand the answer. For example, I have not studied cardinals and ordinals. But I accept your answer as the one that provides more information.
Aug
16
accepted Can a set have a subset which doesn't exist?
Aug
16
revised Self-studying through an undergraduate math course. Need Tao-like textbooks!
deleted 3 characters in body
Aug
16
awarded  Excavator
Aug
16
revised Self-studying through an undergraduate math course. Need Tao-like textbooks!
added 156 characters in body
Aug
15
comment Is isomorphism symmetric?
@AsafKaragila: I don't want to make too much of a point form it. But that passage from Jech's book I mentioned in my question is really confusing. And also you said you had never seen the word range used this way. Now you can no longer say it.
Aug
15
comment Is isomorphism symmetric?
@AsafKaragila: I was just reading Strichartz's "The Way of Analysis" (not old, year 2000). On page 111 the author introduces functions and uses the word range when obviously talking about codomain. He writes: "We don't require that every point in range actually occurs as $f(x)$ for some $x$ in the domain." Instead of range (how we interpret it) he uses image.
Aug
13
comment Is isomorphism symmetric?
@PatrickDaSilva: (Read the previous comment.)
Aug
13
comment Is isomorphism symmetric?
@AsafKaragila: Just read in Mendelson's "Introduction to Topology" on page 13: "Let $f:A \longrightarrow B$ be given. $A$ is called the domain of $f$. $B$ is called the range of $f$."
Aug
13
comment Can a set have a subset which doesn't exist?
@TobiasKildetoft: It seems to me that when you apply AC on a set $S$, you get a set $P$ such that $P \subseteq \bigcup S$, not $P \subseteq S$ as was required.
Aug
13
revised Can a set have a subset which doesn't exist?
deleted 2 characters in body
Aug
13
asked Can a set have a subset which doesn't exist?
Aug
12
comment How much mathematics should a student of mathematical logic know?
First read this guide: logicmatters.net/tyl
Aug
12
asked A better way to define $\bigcap S$?
Aug
12
comment Can't understand an exercise concerning equivalence relations
@900sit-upsaday: Is it a violation of the rules to upload a picture that contains math notation rather that copy everything from the picture in MathJax?
Aug
12
comment Can't understand an exercise concerning equivalence relations
@5xum: What should I have done with MathJax?
Aug
12
accepted Can't understand an exercise concerning equivalence relations