6 ms·

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

by non- 2y ago

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 2y ago
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 2y ago
  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 2y ago
    This reminds me of the time when searching for “c string” would probably result in “The C Programming Language” at number 1.
    - rahkiin 2y ago
      That’s what I get right now
      - dhosek 2y ago
        In the early days of the internet, searching for things like C++ was really challenging because none of the first generation search engines could search for that particular string.
  - eesmith 2y ago
    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 2y ago
    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"
- ssl-3 2y ago
  Eons ago, I was exploring ways to run some outdoor overhead wire between my house and the shed. One method I considered involved using those little self-wedging widgets that squeeze down tighter as the thing being suspended is pulled harder. (These widgets were once commonly used with overhead POTS telephone lines.) So I asked around and the broad consensus in my area was that one of these widgets is called a "horse cock." And while everyone who knew what I was talking could say it with a very straight face, I did not even bother with trying to Google "horse cock" before deciding to go in a different direction with that project.
  - gnopgnip 2y ago
    Is that the same as a kellums grip or hubbell device?
    - ssl-3 2y ago
      A Kellems grip is a Chinese finger trap-like thing made with steel wire. Those are useful, but are very different from a horse cock. A horse cock can also be known as an overhead service entrance wedge clamp, which is a surprising mouthful of nomenclature given the parlancial context. (I don't know what a Hubbell device is -- searching for that just brings up a million wiring devices (outlets, switches, and such) made by Hubbell. But maybe that's the point?)
- stroop 2y ago
  I once noticed a LaTeX installer installing a package called he/she (apparently some sort of pronoun swapper). "Latex he/she" is not great for work search history.
- moomin 2y ago
  Back in the day, a gay colleague of mine forgot the dash in the website of the then trading venue Chi-X. He got a very threatening page in his browser. I assured him I'd back him up in the disciplinary. What was particularly funny was his look of complete incomprehension at why he was getting this message.
causal 2y ago
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 2y ago
  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 2y ago
At least you can send claude or openai images now of the math symbol.
gengelbro 2y ago
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 2y ago
As a first foot-hold I recommend highly https://detexify.kirelabs.org/classify.html 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 2y ago
  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 hν.
  - 12thhandyman 2y ago
    Always thought it was kind of cool how Feynman writes about, when learning calculus and maths as a younger student, would create and use his own symbols for things and how it worked well for him. But kind of realized if he was going to enter the scientific community would need to conform to the standardized notation/symbols for equations etc.
  - crdrost 2y ago
    We solved that though, it's now pronounced “(h)aitch-bar-o-mega.”
    - nine_k 2y ago
      Everything is easier with a piece of pi!
- teddyh 2y ago
  See also: <https://shapecatcher.com/ https://shapecatcher.com/>
- non- 2y ago
  This is great, thank you! Would be even better if it had a little "click here to hear it said out loud" button.
madcaptenor 2y ago
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 2y ago
  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.
  - dhosek 2y ago
    Classical music is relatively standardized. Roman numerals to indicate position are standard practice for all string instruments (I remember learning this as a beginning bass player as a kid). You will sometimes see Roman numerals used as a means of identifying chords relative to the tonic of the current key, but that’s uncommon and the notation is a bit different than the position notation in how it’s placed on the staff (if it even appears on the staff and not in a harmonic analysis).¹ I’ve not seen the upper- and lower-case distinction in roman numeral notation I learned somewhere which uses cases to distinguish between major and minor in any classical music harmonization texts, but I may have just paid insufficient attention. ⸻ 1. I have a vague notion that it might show up in figured bass once in a great while, but I could be wrong.
    - madcaptenor 2y ago
      This all seems right to me. As for your figured bass comment, you could have something like iii^6_4 for an e minor chord with the B in the bass, when the key is C major. But if you were writing it next to the staff you wouldn’t need to write the iii - it’s implied by the bass note and the figures, and classically figured bass writes the minimum it has to, for example just 6 instead of 63 for a first-inversion triad.
column 2y ago
But nowadays you can simply ask a vision model
- jacobr1 2y ago
  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 2y ago
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!!!
- jltsiren 2y ago
  The standard is based on the expectation that you should be able take a definition or a theorem out of its context and it should still make sense. The same symbols are often used for different things in different contexts, while concepts (even advanced ones) tend to remain unambiguous. R is unambiguous if it's in blackboard bold, but otherwise it can mean almost anything. n is likely interpreted as a non-negative integer if left undefined, but you usually need to establish explicitly if it can be 0.
Symbiote 2y ago
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 https://en.wikipedia.org/wiki/%e2%84%98 (manually URL-escaped for HN)
- anyfoo 2y ago
  That assumes you are in a position of being able to paste the character (and as unicode), which is not always the case.
- zamadatix 2y ago
  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 2y ago
> 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 2y ago
  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 2y ago
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 2y ago
  "del" is the only way
  - gjm11 2y ago
    Except that "del" is also (and I think more commonly) the name for the upside-down Delta used in vector calculus for div, grad and curl. (I usually say "partial dx by dt" or whatever, which seems OK to me.)
manvillej 2y ago
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 2y ago
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 2y ago
  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/ 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/ https://www.unicode.org/Public/16.0.0/charts/
- wbl 2y ago
  Once there was a lecture at Yale, and Serge Lang, a frequent loud critic of bad notation was in the audience. There was a function Xi, and soon it was joined by its complex conjugation. Then they were divided. Serge Lang walked out.
xg15 2y ago
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)
- deleted 2y ago
  [deleted]
- jacobolus 2y ago
  "Bold R" and "Double-Lined R" (i.e. blackboard bold) are semantically equivalent. As your next paragraph hints toward, the purpose of the second one is to be distinguishable from the regular italic or Roman 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. The basic issue is that using single symbols for variables is very convenient (both more concise and less ambiguous than writing out full or abbreviated words when writing complicated mathematical expressions), but there are infinitely many possible variables and only a small set of symbols.
  - dhosek 2y ago
    Yes and no. Generally blackboard bold has come to denote particular number sets while bold usually refers to vectors or matrices. There are a handful of traditionalists¹ who will use *R* for the reals or *Z* or even Z for the integers, but the trend toward blackboard bold is, I think, definitely where things are going. ⸻ 1. I would put Donald Knuth in that category, given his choice to not include blackboard bold in his original inventory of characters for Computer Modern, but that might just as much have been a choice based more on limitations of the computing systems he was working with at the time (or his needs for typesetting The Art of Computer Programming which were the primary driver of TeX).
jansan 2y ago
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 2y ago
Well rarely do you see a symbol with zero context. You're reading something. "Oh this has something to do with Weierstrass...."
raldi 2y ago
If you can get it on your clipboard, you can usually paste it into Google or append to `https://en.wikipedia.org/wiki/ https://en.wikipedia.org/wiki/` and get the answer.
anigbrowl 2y ago
This is something I dislike intensely about pro mathematicians. If you need that many symbols, document them properly and work to ensure they're on the flyleaf of every mathematics textbook. You can easily picture a math paper that reads like [ ], but [ ]; however [ ] and [ ], so [ ].... with the spaces being filled in by signatures of famous mathematicians.
omega3 2y ago
Claude worked it out from that description.
max_ 2y ago
I keep on saying that math is not hard. It's just so disorganised that it's hard for people who are not passionate about it to study.
tombert 2y ago
It’s what drives me nuts about people making custom operators on Haskell. A word is easy to search, but something like “~~>>=>” doesn’t really give anything and it’s not nearly as cute as the writers of the libraries seem to think it is. I know about Hoogle but that’s not a solution, as that only searches documentation, not stuff like Stackoverflow.
- tome 2y ago
  I randomly chose *> to search for on Google. It does pretty well, and yes, the top result is StackOverflow. https://www.google.com/search?q=*%3E&iflsig=AL9hbdgAAAAAZzeBiBlxaFwfupjHw3AZPuAADtpstQRD https://www.google.com/search?q=*%3E&iflsig=AL9hbdgAAAAAZzeB...*
  - tombert 2y ago
    Huh, fair enough, I feel like that must be recent because I was having trouble with that before, but maybe it was never as bad as I thought it was. I'll admit I was wrong!
5040 2y ago
I was asking ChatGPT about a "squiggled s" yesterday. It thought I meant ß, but the character I was actually interested in was §. Context was obscure keyboard layouts.
noman-land 2y ago
Local LLMs have helped me a lot in this regard. Even something as simple as "how do I say this formula out loud in words?" helps tremendously.
nox101 2y ago
I was going to say "Use Google Lens" but then I tried it on the character above and it utterly failed :D In any case, there are lots of camera based apps for either OCR (So you could maybe search for the character) or image search or LLM search (I didn't try ChatGPT). I did try zooming 300% and grabbing that character as well as the whole title as an image at 100% zoom with Google Lens. It still failed in both cases.

by non- 2y ago

pflenker 2y ago

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 2y ago
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 2y ago
  This reminds me of the time when searching for “c string” would probably result in “The C Programming Language” at number 1.
  - rahkiin 2y ago
    That’s what I get right now
    - dhosek 2y ago
      In the early days of the internet, searching for things like C++ was really challenging because none of the first generation search engines could search for that particular string.
- eesmith 2y ago
  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 2y ago
  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"
ssl-3 2y ago
Eons ago, I was exploring ways to run some outdoor overhead wire between my house and the shed. One method I considered involved using those little self-wedging widgets that squeeze down tighter as the thing being suspended is pulled harder. (These widgets were once commonly used with overhead POTS telephone lines.) So I asked around and the broad consensus in my area was that one of these widgets is called a "horse cock." And while everyone who knew what I was talking could say it with a very straight face, I did not even bother with trying to Google "horse cock" before deciding to go in a different direction with that project.
- gnopgnip 2y ago
  Is that the same as a kellums grip or hubbell device?
  - ssl-3 2y ago
    A Kellems grip is a Chinese finger trap-like thing made with steel wire. Those are useful, but are very different from a horse cock. A horse cock can also be known as an overhead service entrance wedge clamp, which is a surprising mouthful of nomenclature given the parlancial context. (I don't know what a Hubbell device is -- searching for that just brings up a million wiring devices (outlets, switches, and such) made by Hubbell. But maybe that's the point?)
stroop 2y ago
I once noticed a LaTeX installer installing a package called he/she (apparently some sort of pronoun swapper). "Latex he/she" is not great for work search history.
moomin 2y ago
Back in the day, a gay colleague of mine forgot the dash in the website of the then trading venue Chi-X. He got a very threatening page in his browser. I assured him I'd back him up in the disciplinary. What was particularly funny was his look of complete incomprehension at why he was getting this message.

causal 2y ago

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 2y ago
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 2y ago

At least you can send claude or openai images now of the math symbol.

gengelbro 2y ago

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 2y ago

As a first foot-hold I recommend highly https://detexify.kirelabs.org/classify.html 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 2y ago
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 hν.
- 12thhandyman 2y ago
  Always thought it was kind of cool how Feynman writes about, when learning calculus and maths as a younger student, would create and use his own symbols for things and how it worked well for him. But kind of realized if he was going to enter the scientific community would need to conform to the standardized notation/symbols for equations etc.
- crdrost 2y ago
  We solved that though, it's now pronounced “(h)aitch-bar-o-mega.”
  - nine_k 2y ago
    Everything is easier with a piece of pi!
teddyh 2y ago
See also: <https://shapecatcher.com/ https://shapecatcher.com/>
non- 2y ago
This is great, thank you! Would be even better if it had a little "click here to hear it said out loud" button.

madcaptenor 2y ago

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 2y ago
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.
- dhosek 2y ago
  Classical music is relatively standardized. Roman numerals to indicate position are standard practice for all string instruments (I remember learning this as a beginning bass player as a kid). You will sometimes see Roman numerals used as a means of identifying chords relative to the tonic of the current key, but that’s uncommon and the notation is a bit different than the position notation in how it’s placed on the staff (if it even appears on the staff and not in a harmonic analysis).¹ I’ve not seen the upper- and lower-case distinction in roman numeral notation I learned somewhere which uses cases to distinguish between major and minor in any classical music harmonization texts, but I may have just paid insufficient attention. ⸻ 1. I have a vague notion that it might show up in figured bass once in a great while, but I could be wrong.
  - madcaptenor 2y ago
    This all seems right to me. As for your figured bass comment, you could have something like iii^6_4 for an e minor chord with the B in the bass, when the key is C major. But if you were writing it next to the staff you wouldn’t need to write the iii - it’s implied by the bass note and the figures, and classically figured bass writes the minimum it has to, for example just 6 instead of 63 for a first-inversion triad.

column 2y ago

But nowadays you can simply ask a vision model

jacobr1 2y ago
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 2y ago

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!!!

jltsiren 2y ago
The standard is based on the expectation that you should be able take a definition or a theorem out of its context and it should still make sense. The same symbols are often used for different things in different contexts, while concepts (even advanced ones) tend to remain unambiguous. R is unambiguous if it's in blackboard bold, but otherwise it can mean almost anything. n is likely interpreted as a non-negative integer if left undefined, but you usually need to establish explicitly if it can be 0.

Symbiote 2y ago

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 https://en.wikipedia.org/wiki/%e2%84%98 (manually URL-escaped for HN)

anyfoo 2y ago
That assumes you are in a position of being able to paste the character (and as unicode), which is not always the case.
zamadatix 2y ago
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 2y ago

> 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 2y ago
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 2y ago

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 2y ago
"del" is the only way
- gjm11 2y ago
  Except that "del" is also (and I think more commonly) the name for the upside-down Delta used in vector calculus for div, grad and curl. (I usually say "partial dx by dt" or whatever, which seems OK to me.)

manvillej 2y ago

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 2y ago

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 2y ago
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/ 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/ https://www.unicode.org/Public/16.0.0/charts/
wbl 2y ago
Once there was a lecture at Yale, and Serge Lang, a frequent loud critic of bad notation was in the audience. There was a function Xi, and soon it was joined by its complex conjugation. Then they were divided. Serge Lang walked out.

xg15 2y ago

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)

deleted 2y ago
[deleted]
jacobolus 2y ago
"Bold R" and "Double-Lined R" (i.e. blackboard bold) are semantically equivalent. As your next paragraph hints toward, the purpose of the second one is to be distinguishable from the regular italic or Roman 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. The basic issue is that using single symbols for variables is very convenient (both more concise and less ambiguous than writing out full or abbreviated words when writing complicated mathematical expressions), but there are infinitely many possible variables and only a small set of symbols.
- dhosek 2y ago
  Yes and no. Generally blackboard bold has come to denote particular number sets while bold usually refers to vectors or matrices. There are a handful of traditionalists¹ who will use *R* for the reals or *Z* or even Z for the integers, but the trend toward blackboard bold is, I think, definitely where things are going. ⸻ 1. I would put Donald Knuth in that category, given his choice to not include blackboard bold in his original inventory of characters for Computer Modern, but that might just as much have been a choice based more on limitations of the computing systems he was working with at the time (or his needs for typesetting The Art of Computer Programming which were the primary driver of TeX).

jansan 2y ago

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 2y ago

Well rarely do you see a symbol with zero context. You're reading something. "Oh this has something to do with Weierstrass...."

raldi 2y ago

If you can get it on your clipboard, you can usually paste it into Google or append to `https://en.wikipedia.org/wiki/ https://en.wikipedia.org/wiki/` and get the answer.

anigbrowl 2y ago

This is something I dislike intensely about pro mathematicians. If you need that many symbols, document them properly and work to ensure they're on the flyleaf of every mathematics textbook. You can easily picture a math paper that reads like [ ], but [ ]; however [ ] and [ ], so [ ].... with the spaces being filled in by signatures of famous mathematicians.

omega3 2y ago

Claude worked it out from that description.

max_ 2y ago

I keep on saying that math is not hard. It's just so disorganised that it's hard for people who are not passionate about it to study.

tombert 2y ago

It’s what drives me nuts about people making custom operators on Haskell. A word is easy to search, but something like “~~>>=>” doesn’t really give anything and it’s not nearly as cute as the writers of the libraries seem to think it is. I know about Hoogle but that’s not a solution, as that only searches documentation, not stuff like Stackoverflow.

tome 2y ago
I randomly chose *> to search for on Google. It does pretty well, and yes, the top result is StackOverflow. https://www.google.com/search?q=*%3E&iflsig=AL9hbdgAAAAAZzeBiBlxaFwfupjHw3AZPuAADtpstQRD https://www.google.com/search?q=*%3E&iflsig=AL9hbdgAAAAAZzeB...*
- tombert 2y ago
  Huh, fair enough, I feel like that must be recent because I was having trouble with that before, but maybe it was never as bad as I thought it was. I'll admit I was wrong!

5040 2y ago

I was asking ChatGPT about a "squiggled s" yesterday. It thought I meant ß, but the character I was actually interested in was §. Context was obscure keyboard layouts.

noman-land 2y ago

Local LLMs have helped me a lot in this regard. Even something as simple as "how do I say this formula out loud in words?" helps tremendously.

nox101 2y ago

I was going to say "Use Google Lens" but then I tried it on the character above and it utterly failed :D In any case, there are lots of camera based apps for either OCR (So you could maybe search for the character) or image search or LLM search (I didn't try ChatGPT). I did try zooming 300% and grabbing that character as well as the whole title as an image at 100% zoom with Google Lens. It still failed in both cases.