What is ¬ called and what is it for?

Question

Googling this question has proved somewhat useless, so the ¬ symbol:

What is it for?
What is is called?
Is it used in any programming languages?

That character is U+00AC NOT SIGN and is one of the many notations for logical negation — amon, Jul 19 '15 at 18:49
I'm voting to close this question as off-topic because it is not about software development concepts as explained in the [help/on-topic]. — amon, Jul 19 '15 at 18:50
It's on a standard UK 101 keyboard, top left with the back tick and the broken pipe¦`. — BanksySan, Jul 19 '15 at 19:26
Wikipedia has redirects for many unicode symbols. ¬. You can also see this with things like https://en.wikipedia.org/w/index.php?title=&redirect=no. While google's search doesn't do a good job with this character, one should try pasting it into Wikipedia's search. They have many redirects for single unicode characters set up. — , Jul 20 '15 at 02:23
Used to break long statements in app script http://alvinalexander.com/mac-os-x/mac-osx-applescript-break-long-lines-keytroke — Maxim Veksler, May 15 '16 at 09:53

score 36 · Accepted Answer · answered Jul 19 '15 at 18:48

36

The only use I've seen for the ¬ symbol is to represent negation in the context of formal logic. For instance, if P is the proposition "It will rain today", then ¬P is the proposition "It will not rain today." I've also seen ~ used for this.

I don't believe it has an actual name other than "negation symbol". Normally it's read as "not".

As far as I know, in programming this symbol has no special meaning, at least not in any mainstream languages I've used.

answered Jul 19 '15 at 18:48

Ixrec

27,771

Some programming languages accept UTF8 characters as names or user-defined operators. – Basile Starynkevitch Jul 19 '15 at 19:17
1

Why is negation symbol not an "actual name"? After all, we call ! exclamation point and ? question mark. And those are perfectly fine names. – Brandin Jan 26 '16 at 19:42
REXX uses ¬ for logical not and in operators like ¬=, ¬>, etc. Most implementation also allow \\ because many keyboards lack a ¬ key. I'm not sure that it can be considered a mainstream language, though. – mrb Aug 08 '16 at 13:33
PL/1 (developed in the late 1960s) used the ¬ symbol for not. Having used PL/1 for many years I still think of this as the not symbol – Kickstart Jul 06 '17 at 10:53
AppleScript uses ¬ as the line-continuation symbol, to split long commands into multiple lines, like \ in bash script. – Chad von Nau Jun 30 '18 at 22:39

What is ¬ called and what is it for?

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