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Dislosure: I'm not directly from the fields of the Sciences Of Angles And Ambiguously Crossing Lines nor I've every seen or used this symbol before. However to
by firstcommentyo 4y ago
Dislosure: I'm not directly from the fields of the Sciences Of Angles And Ambiguously Crossing Lines nor I've every seen or used this symbol before. However to me it's, pretty evidently, supposed to be a "no right angle" symbol.
(A) It's in the math section,
(B) it's with angles,
(C) the thunderbolt ↯ is commonly used for "not" or more specifically for dis-proof in this area and
(D) at least by my 30 s internet search on a mobile phone I couldn't find any other "no-angle" or "no-right-angle" symbol.
Someone could argue that usually you use a simple strike through as like as in ≠ (unequal), ∉ (not-element-of) or ∅ (empty set) but I would say it was chosen to avoid confusion in this case. The angle itself (without the "no/not") consists of only to orthogonal lines so it would be kinda complicated to "strike it though" in any direction without ambiguity that would resemble a triangle, a fork or whatnot.
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- froh 4y agoPerpendicular + Unicode combining solidus = ⟂ + / = ⟂̸
- r0uv3n 4y agoI think perpendicular most commonly refers to lines/vectors/planes etc., while the right angle symbol refers to angles. Also, there are often multiple symbols expressing the same thing.
- froh 4y agoYes, a sibling comment meanwhile found the right angle symbol U+221F ∟ https://news.ycombinator.com/item?id=31015104 https://news.ycombinator.com/item?id=31015104
- mizzao 4y agoReminds me of https://xkcd.com/2606/ https://xkcd.com/2606/ Explained: https://www.explainxkcd.com/wiki/index.php/2606 https://www.explainxkcd.com/wiki/index.php/2606
- mbauman 4y agoThat doesn't jive with the history in TFA — the Unicode name and location was inferred from the symbol itself without knowledge of its meaning.
- dundarious 4y agoI don't see the contradiction. The only thing they used from the name is the "right angle" aspect. Given their argument is this is a composition of thunderbolt + X, for some X (and derived from their prior knowledge of thunderbolt's compositional meaning), deciphering the image as "thunderbolt + right angle" is trivial and consistent with the naming origin in TFA.
- zeteo 4y ago> (C) the thunderbolt ↯ is commonly used for "not" or more specifically for dis-proof in this area Any examples?
- firstcommentyo 4y agoHigh school physics and math as a major. I could scan you my scripts and papers if you're interested.....no won't. ;-D But maybe "commonly used" was maybe the wrong term. More appropriately: "sometimes" or "by some".
- IshKebab 4y agoI have never seen it used as not once in maths or physics. "extremely rarely" perhaps.
- mywittyname 4y agoTo be fair, there are lot of math symbols out there. http://mirrors.dotsrc.org/ctan/info/symbols/comprehensive/symbols-a4.pdf http://mirrors.dotsrc.org/ctan/info/symbols/comprehensive/sy... There are lots of examples of the lightning bolt in there. In fact, under ulsy Contradiction symbols, there are four variants. I also noticed the exact symbol being discussed is listed under "Angles".
- renewiltord 4y agoWhere in the world? I’ve never used it despite similar background. Perhaps regional?
- HuangYuSan 4y agoI believe in German (possibly also other languages) the thunderbolt ↯ is commonly used to mean "this is a contradiction" in a mathematical proof, equivalently to in English a kind of ⋕ rotated by 45° or the symbol ※. The symbol ⟂ on the other hand means "false" and is used in particular in formal logic.
- 4y ago
- _haoa 4y agoRight angles have a small box near the vertex which denotes it is a right angle [0]. This symbol doesn't have that box, so I don't think it's a right angle. [0] https://en.wikipedia.org/wiki/Right_angle#/media/File:Right_angle.svg https://en.wikipedia.org/wiki/Right_angle#/media/File:Right_... Edit: This merely adds to the confusion, since the name of the glyph contains the words "right angle." ¯\_(ツ)_/¯
- mikeryan 4y agoThis merely adds to the confusion, since the name of the glyph contains the words "right angle." The article notes that sans a given meaning the glyph was given a “descriptive name”. So you’re not wrong? :-P
- cgriswald 4y agohttps://en.wikipedia.org/wiki/Right_angle https://en.wikipedia.org/wiki/Right_angle > In Unicode, the symbol for a right angle is U+221F ∟ RIGHT ANGLE (HTML ∟ · ∟). It should not be confused with the similarly shaped symbol U+231E ⌞ BOTTOM LEFT CORNER (HTML ⌞ · ⌞, ⌞). Related symbols are U+22BE ⊾ RIGHT ANGLE WITH ARC (HTML ⊾ · ⊾), U+299C ⦜ RIGHT ANGLE VARIANT WITH SQUARE (HTML ⦜ · ⦜), and U+299D ⦝ MEASURED RIGHT ANGLE WITH DOT (HTML ⦝ · ⦝).[5] > In diagrams, the fact that an angle is a right angle is usually expressed by adding a small right angle that forms a square with the angle in the diagram, as seen in the diagram of a right triangle (in British English, a right-angled triangle) to the right. The symbol for a measured angle, an arc, with a dot, is used in some European countries, including German-speaking countries and Poland, as an alternative symbol for a right angle.[6]
- aaron695 4y ago
- esperent 4y ago> the thunderbolt ↯ is commonly used for "not" or more specifically for dis-proof in this area and I don't think it's that common. At least, I don't recall seeing it ever. Maybe it's used in non-English mathematics? Wikipedia mentions it's also used in electrolysis so maybe this new one is related to that somehow?
- maze-le 4y agoIt's used in german mathematics education (secondary level), either to mark a contradiction in a proof or more generally to mark an erroneous statement.
- deleted 4y ago[deleted]
- ruuda 4y agoAlso in Dutch universities to mark a contradiction, especially in a proof by contradiction.
- dirkt 4y agoBut I have never seen it to mark negation of a condition, that's usually done with a slash (as in ≠ ≮ ≯ ≰ ≱ ≴ ≵ ⊄ ⊅ ⊈ ⊉ ⊊ ⊋ ∉ ∌ ∄ ∦, you get the idea). So for "not a right angle" I'd have expected a "right angle" symbol with a slash through it.
- maze-le 4y agoFunny enough, I've only seen it at the Gymnasium (secondary level) and not in the University a few years later -- then indeed the usual symbols were the 'slashed' relations like you've described, or the bottom symbol: ⊥ in logic. Maybe it's an idiosyncrasy of a certain subset of math teachers.
- r0uv3n 4y agoBut how would you position the slash to get a somewhat easy to decipher symbol? To me, the right angle symbol seems to lend itself more to this unorthodox negation through the contradiction symbol than to negation through the normal slash.
- danparsonson 4y agoI submit to you that it's clearly not a thunderbolt but an arrow indicating changing directions; that being overlaid on top of a pair of axes is obviously useful in the study of non-Euclidean geometry to indicate the use of wibbly-wobbly dimensions.
- kens 4y agoI've thought that it would be cool to have a Wiki with an entry for each character, describing what it is, and its history. Although that wouldn't help for mystery characters like this one, there are a lot of characters with stories behind them.
- sprayk 4y agoI like this idea. It would serve as a place to put a well-sourced answer to the question about this character, and the talk section could be used to discuss further investigation into the topic, or when new uses inevitably arise.
- paledot 4y agoI was just discussing :man-in-business-suit-levitating: with some friends earlier today. Also an interestingly cryptic background, albeit not an unsolved one. https://emojipedia.org/person-in-suit-levitating/ https://emojipedia.org/person-in-suit-levitating/ (Edit: Apparently HN automatically removes emoji.)
- logbiscuitswave 4y agoThe story behind MIBSL is definitely fascinating and some great trivia there. There’s a longer article about it here: https://www.newsweek.com/2016/05/06/secret-ska-history-man-business-suit-levitating-emoji-442192.html https://www.newsweek.com/2016/05/06/secret-ska-history-man-b... that covers not just the inspiration for the emoji itself, but a brief history behind the inspiration behind the inspiration. Lots of levels of metaness to unpack.
- alx__ 4y agoI love this! I've always assumed it was a rude boy emoji. Was briefly in a high school ska band :D
- subroutine 4y agoWikipedia already does this for many symbols. See for example... https://en.wikipedia.org/wiki/Miscellaneous_Technical https://en.wikipedia.org/wiki/Miscellaneous_Technical Aside from the table describing each symbol, if you scroll to the bottom of the page, it links out to full articles related to each. For a full list see... https://en.wikipedia.org/wiki/List_of_Unicode_characters https://en.wikipedia.org/wiki/List_of_Unicode_characters
- HNHatesUsers 4y ago