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How would one pronounce an expression involving a set symmetric difference, such as $A\triangle B$? Would that be read "A symmetric difference B?" Or perhaps something like "A xor B?"

This came up when I was teaching a course involving elementary set theory and I was having trouble reading statements like $A \cup (B \triangle C)$ out loud.


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closed as primarily opinion-based by Najib Idrissi, cactus314, quid, Tom-Tom, Justpassingby Dec 14 '15 at 16:28

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

$A$ "triangle" $B$ seems fine too, if context is clear. I read $A\cap B$ as "$A$ cap $B$" and similarily for $A\cup B$. Seems to ease things off. – Pedro Tamaroff Sep 17 '12 at 22:39
I read $A \cup B$ as "$A$ union $B$" and $A \cap B$ as "$A$ intersect $B$" – Dilip Sarwate Sep 18 '12 at 1:08
up vote 7 down vote accepted

Just because something is written in a certain order doesn't mean it has to be pronounced that way. For instance, when you say '£5' (or '$5' if you're that way inclined), you'd say 'five pounds' (or 'five dollars'), rather than 'pounds five' (or 'dollars five').

The same applies here. $A \triangle B$ denotes 'the symmetric difference of $A$ and $B$', and that is a perfectly good way of pronouncing it.

Edit (in response to the latest edit to the question): Likewise $A \cup (B \triangle C)$ could be pronounced 'the union of $A$ [with/and] the symmetric difference of $B$ and $C$', or perhaps '$A$ union the symmetric difference of $A$ and $B$'.

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I would say "the symmetric difference of $A$ and $B$." In certain contexts "$A$ xor $B$" would work too.

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As a student, if I am writing what the lecture reads I would prefer to hear $A$ symmetric difference $B$ since it would save me the time in having to 'translate it' when I write it in my notebook (when I tooked set theory it was said in this way)

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