[HN Gopher] The letter : name and origin? (2017)
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The letter : name and origin? (2017)
Author : IdealeZahlen
Score : 171 points
Date : 2024-11-14 16:28 UTC (6 hours ago)
(HTM) web link (mathoverflow.net)
(TXT) w3m dump (mathoverflow.net)
| non- wrote:
| One thing I've always struggled with Math is keeping track of
| symbols I don't know the name of yet.
|
| Googling for "Math squiggle that looks like a cursive P" is not a
| very elegant or convenient way of learning new symbol names.
|
| I wish every proof or equation came with a little table that gave
| the English pronunciation and some context for each symbol used.
|
| It would make it a lot easier to look up tutorials & ask
| questions.
| pflenker wrote:
| I can relate. Ages ago, before Safe Search and search result
| tailored to one's history and preferences, I was trying to
| figure out how to write that big union symbol ([?]) in LaTeX
| and googled for Big Cup LaTeX. I got _very_ different and
| unexpected results.
| vundercind wrote:
| Googling guitar-related stuff is how I learned there's such a
| thing as c-string women's underwear & bathing suit bottoms,
| not just g-strings.
|
| That was, briefly, a real WTF moment.
|
| [edit] oh my god, of course that one didn't come from
| searching guitar topics, that makes no sense given the
| standard tuning. I'm pretty sure I was googling strings in
| the C language when I hit that one, lol. I did probably
| accidentally land on "g string" after searching without
| thinking about what would obviously come up, when looking up
| guitar topics, and must have combined the two incidents in my
| memory.
| Archelaos wrote:
| This reminds me of the time when searching for "c string"
| would probably result in "The C Programming Language" at
| number 1.
| rahkiin wrote:
| That's what I get right now
| eesmith wrote:
| Back in the mid-1990s I extracted a small part of the GNU
| C++ String library into a small package, which I called
| "GString".
|
| I had no idea about the garment.
| scubbo wrote:
| Haha - my favourite WTF Googling moment was when, as a
| callow youth first setting out in learning Javascript and
| HTML, I Googled "How to get head"
| causal wrote:
| Yeah I find that I reason about math in my head with names for
| symbols - the visual shape is not sufficient for the math part
| of my brain to manipulate it as a symbol.
| mindcrime wrote:
| Same. If I see a symbol and can't "say" the symbol, I can't
| (easily) process it. I think over time that gets better and
| eventually it's possible to start to "pattern match" it just
| off the visual representation, but at least for me when
| something is new, I need the "name" of it as something I can
| say to myself or I hit a ParseException. :-(
| narrator wrote:
| At least you can send claude or openai images now of the math
| symbol.
| gengelbro wrote:
| There has been various modernization efforts in the past
| correct? I wonder why nothing has succeeded. Math has always
| been somehow very tied to keeping credit and personal
| achievement close to the "source" it feels. Conjectures always
| coming with names attached, or this symbol named after a
| whimsical stoke of a pen.
| loremm wrote:
| As a first foot-hold I recommend highly
| https://detexify.kirelabs.org/classify.html
|
| (I think I saw there was a newer one, but don't remember how)
|
| You draw the symbol and get the TeX symbol name. I tried this
| one and it does give the right \wp (which in this case is
| confusing and you'd have to look up more about why it's named
| that)
|
| But for classic ones, for instance the "upside down A" ->
| "forall" is very helpful and shakes newcomers to math syntax
| nine_k wrote:
| Feynman said that his students struggled with a reverse
| problem: how to know that "harnew", an important part in QM
| equations that the lecturer talks about, actually stands for
| _hn_.
| teddyh wrote:
| See also: <https://shapecatcher.com/>
| non- wrote:
| This is great, thank you! Would be even better if it had a
| little "click here to hear it said out loud" button.
| madcaptenor wrote:
| I have seen math textbooks that have a "table of symbols" or
| similar, by the table of contents or the index. It's really
| helpful. Also nice to have - a "map of the book" (I don't know
| a better name for this) which indicates graphically which
| sections of the book depend on which other sections.
| "Dependency graph", maybe?
| QuercusMax wrote:
| I wish music books would do this too - I've been self-
| teaching myself a little classical guitar, and some of the
| scores I'm reading have various symbols that have taken me
| quite a while to figure out. I eventually determined that a
| bold III means to play in third position in some books, but
| these things aren't consistent between publishers.
| column wrote:
| But nowadays you can simply ask a vision model
| jacobr1 wrote:
| yep, or even just a text model
|
| ChatGPT 01-preview gave me:
|
| User: what is the Math squiggle that looks like a cursive p?
|
| Assistant: The mathematical symbol you're referring to is
| likely the Weierstrass \wp function symbol, which resembles a
| cursive or script "p":
| graycat wrote:
| Uh, symbols and math??? Uh, as I read mathematical physics, I
| get the impression that certain symbols in certain equations
| are accepted throughout physics as already defined. But in
| math, we have, e.g.,
|
| "For the set of real numbers R, some positive integer n, and
| R^n, with both R and R^n with the usual topologies and sigma
| algebras, we have function f: R^n --> R, Lebesgue measurable
| and >= 0."
|
| That is, in writing in math, a popular but implicit standard
| is, each symbol used, even if as common as R and n, is defined
| before being used.
|
| Sooooo, right there in the math writing, the symbols are
| defined. Or, right, an author might assume that the reader
| knows what "the usual topology" or "Lebesgue measurable" are
| but does not assume the reader knows what the symbols mean.
| I.e., the issue is not something about helping readers with
| their knowledge of math but, instead, just being clear about
| the symbols. Or, can assume the reader DOES know about the real
| numbers but does NOT assume that R is the set of real numbers
| -- and correctly so because R might be the set of rational
| numbers, some group (from abstract algebra), nearly anything.
|
| Again for physics, E = mc^2 and J = ns^2 are not the same, not
| within the standards, maybe even if say J is energy in Joules,
| n is mass, and s is the speed of light!!!
| Symbiote wrote:
| The "unicode" program (in Ubuntu's package repository) gives
| the Unicode entry for any character: $ unicode
| U+2118 SCRIPT CAPITAL P UTF-8: e2 84 98 UTF-16BE: 2118
| Decimal: ℘ Octal: \020430 Category: Sm
| (Symbol, Math); East Asian width: N (neutral) Unicode
| block: 2100..214F; Letterlike Symbols Bidi: ON (Other
| Neutrals) Age: Assigned as of Unicode 1.1.0 (June, 1993)
|
| Or you can ask Wikipedia:
| https://en.wikipedia.org/wiki/%e2%84%98 (manually URL-escaped
| for HN)
| anyfoo wrote:
| That assumes you are in a position of being able to paste the
| character (and as unicode), which is not always the case.
| zamadatix wrote:
| If you already have a copyable version of the character it
| also works in the original Google search. Or any other place
| you can put it. The problem is when you don't have the
| literal character as text (say, an image, video, or non-
| digital source) and need to reproduce it to do that lookup in
| the first place.
| layer8 wrote:
| > Googling for "Math squiggle that looks like a cursive P" is
| not a very elegant or convenient way of learning new symbol
| names.
|
| Asking ChatGPT (or the like) is a good solution nowadays
| though: "The mathematical symbol that resembles a cursive "p"
| is likely the Weierstrass p, denoted as . [...]"
| flatline wrote:
| I asked once and it just gave me "p". I said "no more fancy
| like" and it produced the correct result. This is the real
| power of the model for narrowing search, you can interrogate
| the results.
| bregma wrote:
| I heard as many names for the "\partial" symbol as I had math
| professors in university. At least they all wrote them the
| same.
| JohnKemeny wrote:
| "del" is the only way
| manvillej wrote:
| I have this little book that I cannot find right now that is
| pretty explicitly that. just a little math symbol dictionary.
| its small enough to fit in a pocket and was invaluable all
| through college.
| mindcrime wrote:
| As somebody who spends a fair amount of time studying math
| heavy material that uses math that I never studied formally,
| this stuff is the bane of my existence. It's one thing to see a
| random Greek letter, where at least I very likely know what the
| character "is" (eg, "rho" or "psi" or whatever) and can at
| least pronounce it to myself and make a mental note "go back
| and see what rho stands for in this equation". But exactly like
| you say "squiggle that looks like a cursive P" doesn't easily
| admit a mental placeholder, AND it's hard to look up later to
| find out exactly what it is. I've really wanted to tear my last
| hair out over this a few times. And I am pretty sure one recent
| such occasion involved this exact character, so this really
| hits home!
|
| And never mind that cognitive load that comes from managing the
| use of symbols that are the "same symbol" modulo something the
| typeface. Trying to read something like
|
| "Little b equals Fraktur Bold Capital B divided by (q times
| Cursive Capital B) all over Gothic Italic B", blah, blah...
| then throw in the "weird little squiggle that looks kinda like
| a 'p' but not quite". It's insane.
| mmooss wrote:
| The Unicode charts for the mathematical symbol ranges can
| serve as a visual index: [0]
|
| They open as PDFs and have grids of all the symbols, along
| with useful metadata such as related and similar symbols,
| common substitutes, alternate names, etc. You won't find
| everything in those ranges - some things are elsewhere in
| Unicode, in their native language or already located
| elsewhere in an earlier version - but it's a great resource.
| Even for symbols that are merely letters in some language's
| alphabet, Unicode sometimes provides a unique codepoint
| (character) for their use in mathematics.
|
| [0] https://www.unicode.org/charts/
|
| That provides each table as a separate PDF downlod:
| mathematics covers ~20 PDFs, each named for its contents. It
| may be faster to download the entire Unicode standard as one
| PDF (~140 MB):
|
| https://www.unicode.org/Public/16.0.0/charts/
| xg15 wrote:
| This. Related to that, I'll also never get used to
| mathematicians' habit to assign semantic meaning to the _font_
| that a letter is drawn in. Thanks to that, we now have R, Bold
| R, Weirdly Double-Lined R, Fake-Handwritten R, Fraktur R and
| probably another few more.
|
| All of those you're of course expected to properly distinguish
| in handwriting.
|
| I'm sure most of them have some sort of canonical name, but I'm
| usually tempted to read them with different intonations.
|
| (Oh and of course each of those needs a separate Unicode
| character to preserve the "semantics". Which I imagine is
| thrilling edgy teenagers in YouTube comments and hackers
| looking for the next homograph attack)
| jacobolus wrote:
| "Bold R" and "Double-Lined R" (i.e. blackboard bold) are the
| same thing. As your next sentence indicates, the purpose of
| the second one is to be distinguishable from the regular R in
| handwriting (or on a typewriter).
|
| "Fake-Handwritten R" is an extra fancy calligraphic version
| which is not hard to distinguish. The Fraktur R is a pain to
| write, but you can write an upright "Re" as an alternative.
| jansan wrote:
| We had a guy in class at high school who was a math prodigy,but
| hated the greek alphabet. He always said things like "If we
| multiply the symbol that I don't know with the square root of
| the other symbol that I don't know..." He was proof for me that
| you can be really good at (high school) math without knowing
| all the symbols' names.
| paulddraper wrote:
| Well rarely do you see a symbol with zero context.
|
| You're reading something. "Oh this has something to do with
| Weierstrass...."
| zusammen wrote:
| I think one's getting a lot of upvotes from people who meant to
| click on the link.
| tim-kt wrote:
| Yes, this happened to me
| dang wrote:
| You can always click 'unvote' in the detail line.
| wduquette wrote:
| I left college with a math degree and a profound antipathy for
| weird cursive symbols. The one that nearly killed me was the
| Greek "xi". I couldn't pronounce it, and I couldn't write it with
| any fluency, and in some of the classes I took it was
| _everywhere_.
| layer8 wrote:
| Despite only having a CS degree, I was always especially fond
| of x due to its distinctiveness (and also didn't have trouble
| writing or pronouncing it), moreso than letters like n or i,
| which are too close to _v_ or _i_ / _j_ visually for my taste.
| anyfoo wrote:
| I think iota is fine because it's missing the dot that an i
| has, but nu is terrible, yeah. In fact, in some fonts nu is
| _exactly_ v: https://en.wikipedia.org/wiki/Nu_(letter)
|
| But then a lot of capital greek letters at least are
| identical to latin letters in those fonts, so I guess you
| have to choose carefully anyway... and pick the proper
| font/handwriting if you absolutely _have_ to use nu.
| (Hopefully you don 't.)
| anyfoo wrote:
| I encounter x (xi), and also z (zeta) a lot. Honestly, when I
| write them out by hand, I just make a "wild squiggly line" for
| x and a "simplified squiggly line" for z.
|
| If I write it out by hand, it's most likely just for my eyes
| anyway, and I'd type it out on a computer if I'd want others to
| have a look at it. But even if I gave someone else my
| handwritten note, I think from context it would be pretty clear
| what the "squiggly lines" are supposed to be.
| Symbiote wrote:
| z is essentially a cursive z. x is near enough to a backwards
| 3.
| andrewshadura wrote:
| x is literally three horizontal bars underneath each other,
| in cursive.
| science4sail wrote:
| I must confess that I have an irrational fondness for the use of
| weird symbols in math and technical documents, whether it's for a
| homework assignment in school or a white-paper for work.
|
| My unit tests are literally full of hieroglyphics. My favorite
| design doc to this day is one where I sprinkled Sumerian
| cuneiform throughout the text, e.g. and (Gilgamesh and Enkidu)
| instead of Alice and Bob.
| a57721 wrote:
| I'm not sure if this is a good idea, especially in code; apart
| from adding unnecessary confusion for the reader, this will
| also confuse some monospaced fonts.
| wil421 wrote:
| Glad I'm not GPs coworker. Time to refactor Gilgamesh.
| gweinberg wrote:
| I just see boxes, not the cuneiform.
| Aloisius wrote:
| I've seen emoji used for Alice/Bob/Carol/etc which is a bit
| more widely supported than old dead scripts.
|
| I await the inevitable mathematical constant unicorn emoji.
| ugurs wrote:
| Strangely, the most comfortable I've felt with symbols was when
| learning quantum computing. At the time, there was no established
| standard (perhaps it has a standard now), but the symbols were
| used more intuitively than any other math class I've taken.
| Symbiote wrote:
| In the same Unicode block is "2129 TURNED GREEK SMALL LETTER
| IOTA" with explanation "unique element fulfilling a description
| (logic)".
|
| That seems a ridiculous choice for a symbol -- turning one of the
| most symmetrical letters upside down!
|
| Background:
| https://philosophy.stackexchange.com/questions/51563/what-is...
| Archelaos wrote:
| It could be motivated by the fact that Russell and Whitehead
| needed a symbol for printing that the printer had in his type
| case but could not be confused with anything else. Taking a
| iota and simply turning it upside down would then be a rather
| ingenious idea. But that is just my speculation ...
| eesmith wrote:
| https://math.stackexchange.com/questions/1885938/whats-
| meani... says 'in the article Frege, Peano and Russell on
| Descriptions: a Comparison, Francisco A. Rodriguez-Consuegra
| tracks down the source to Peano's Studii di logica matematica
| (1897) as where the operator first appears'
|
| That page in 'Studii di logica matematica' appears to be
| https://archive.org/details/peano-studii-di-logica-
| matematic... .
|
| It also uses an upside-down C and upside-down E.
| schoen wrote:
| In the font on my phone it looks confusingly reminiscent of
| Hebrew vav.
| hinkley wrote:
| My first thought on seeing this title was, "this should totally
| be the name of a programming language descended from Go"
| xg15 wrote:
| "The letter formerly known as p"
| cubefox wrote:
| One thing I like about programming languages is that they usually
| constrain themselves to strings of ASCII characters, instead of
| using lots of more or less inscrutable symbols like mathematics
| does. For example, where a mathematician writes "S", a programmer
| simply writes "sum".
| mmooss wrote:
| You are holding up code as an example of clarity and
| scrutability, and because it is mostly restricted to ASCII? Hex
| code is even simpler - only 16 characters.
|
| > where a mathematician writes "S", a programmer simply writes
| "sum".
|
| Communities develop shorthand and terms of art for things they
| write a lot. Mathematicians need to write lots of sums;
| programmers have their own shorthand and terminology.
| zahlman wrote:
| >>> import unicodedata >>> unicodedata.name('')
| 'SCRIPT CAPITAL P' >>> ord('') 8472
|
| https://en.wikipedia.org/wiki/Letterlike_Symbols
|
| Good enough for me.
|
| Notably, this is distinct from ("MATHEMATICAL SCRIPT CAPITAL P").
|
| > Books were printed in Fraktur, where the p looks quite normal,
| i.e., quite different from a handwritten Sutterlin p which could
| explain, why it hasn't been replaced in the publication of
| Amandus Schwarz.
|
| Indeed. ("MATHEMATICAL FRAKTUR CAPITAL P") is also separate (but
| also, Unicode considers these mathematical symbols to exist
| separately from "text written in Fraktur script". So you get
| separate characters allocated for these symbols, but they're not
| intended to be suitable for printing in Fraktur - which is
| supposedly a presentation (i.e. typeface selection) issue.
|
| Personally I'm not convinced that mathematical symbols derived
| from Latin or Greek (or other) scripts really have any claim to
| being separate "characters". Surely that's what variation
| selectors are for?
| robinhouston wrote:
| I think the answer by teika kazura on the linked page explains
| pretty thoroughly why this is not "good enough". Most
| importantly:
|
| > In Unicode the letter is given the codepoint U+2118 in the
| block "letterlike symbols", named "script capital p". But in
| fact it's lowercase.
|
| Unicode technical note https://www.unicode.org/notes/tn27/
| clarifies:
|
| > Should have been called calligraphic small p or Weierstrass
| elliptic function symbol, which is what it is used for. It is
| not a capital "P" at all. A formal name alias correcting this
| to WEIERSTRASS ELLIPTIC FUNCTION has been defined.
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