Talk:Epsilon

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At first line of the article the unicode symbol given for epsilon is actually 'LATIN SMALL LETTER OPEN E' (U+025B). It's confusing when one uses this article for copying the letter to eg. computer program where the code matters, not only the shape. — Preceding unsigned comment added by 82.131.27.253 (talk) 12:30, 21 March 2015 (UTC)Reply

In LaTeX there are two epsilon characters: \epsilon and \varepsilon. The variant version is the one described on the page, but there's no mention of LaTeX's normal epsilon character. I know I've always seen \epsilon used for describing set membership, but \varepsilon for describing small numbers. Can someone add more authoritative information explaining the difference in usages? 192.160.6.252 20:00, 10 Mar 2005 (UTC)

I don't know the answer to your question, but I can say that LaTeX's \epsilon, ${\displaystyle \epsilon \,\!}$, is different from its set membership symbol, \in, ${\displaystyle \in \,\!}$. —User:Caesura^(t) 14:43, 21 November 2005 (UTC)Reply

I added a short description of the Lunate Espilon. As far as I know, the two are effectively interchangeable, although there might be some deeper distinction between two in more formal usage. Pagasaeus 06:29, 30 November 2006 (UTC)Reply

Maybe it's just my font, but it isn't clear which is the normal epsilon (${\displaystyle \varepsilon }$?) and which is the lunate epsilon (${\displaystyle \epsilon }$?); The latter symbol is used almost exclusively in the first paragraph. Since fonts can vary, perhaps a small picture would be helpful. --ScottAlanHill 15:11, 5 March 2007 (UTC)Reply

Right now the article appears to contradict itself. It claims that "The standard symbol for lowercase epsilon is the lunate epsilon", but shows an open one in the infobox image. If the two shapes are indeed interchangeable in ordinary typography (like the open-tail and loop-tail forms of 'g' in Latin script), the article should not claim that one is "standard". Or is it more like the difference between upright and italic Latin 'a'? –Henning Makholm 01:08, 1 January 2008 (UTC)Reply

This currently appears as a contradiction on my screen:

In TeX, \epsilon (ε) denotes the lunate form.

The parenthetical example there (which in the article source is created using TeX code) does not produce the lunate form. The \varepsilon is an obvious, "fancier" variation, but neither produces the lunate (ϵ). Whether a font issue, a TeX implementation issue, or some other problem, we can assume that it appears incorrect to others, as well.

Are we sure that TeX specifies the lunate form for \epsilon? Either way, I'd probably recommend not saying so, at least until we figure out what's up here. /ninly_(talk) 20:13, 31 August 2010 (UTC)Reply

Trying to find symbol for nonparametric hypotesis test. It is either Epsilon or Pi. Any ideas? 3.1415926535897932384626433...

What is the meaning of the first two sentences of the third paragraph: "Epsilon is one the six numbers that fomulate the universe that make the universe suitable for life within the cosmos.The founder of the sixe numvers is Rees J. Martin." ? This seems vague, misspelled and/or simply incorrect or misleading..

From introduction section "The lunate epsilon ϵ is not to be confused with the set symbol ∈." However the Symbol section states "In mathematics, set membership (often written ∈ instead of ε)." I believe that the latter definition should be deleted. The set symbol is NOT an epsilon, it is just a generic mathematical symbol. 220.233.204.250 05:42, 4 August 2007 (UTC)Reply

• I agree; I've removed it. --ScottAlanHill 06:58, 5 August 2007 (UTC)Reply

Epsilon Tekstil ve Çanta üzerine kurulmuş bir firma. 1986 den beri varlar. daha geniş bilgi için: http://www.epsilon.com.tr —Preceding unsigned comment added by 85.96.136.247 (talk) 12:57, 15 June 2009 (UTC)Reply

SO it says this is semi-protected indefinitely due to high risk of vandalism. There doesn't seem to be any that has happened recently and there is no mention of any on the talk page. Why not lock down every article since someone MIGHT vandalize them too?

Hello?

Looks like no one is looking at your comment. There are some other Greek letters that are locked. There isn't any consistency or reason stated. Looks like the admins that locked it dropped the ball.

Rather than the Greek epsilon being favored, and with as many other things (companies, languages, etc.) known simply as "Epsilon", having them all routed through this article doesn't make much sense. With "Epsilon" being a significant news item, it shouldn't be this difficult to discover that nobody has created an entry for the company yet. Merennulli (talk) 17:06, 4 April 2011 (UTC)Reply

I'd like to know why there isn't a disambiguation page somewhere... Epsilon (disambiguation) doesn't exist, and there are so many possible articles. 70.24.248.23 (talk) 11:14, 15 November 2011 (UTC)Reply

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Deacon Vorbis, sorry, I don't understand your rollback. The text (you removed) said nothing about Halmos, only about modern usage. (1) Nowadays, we write x∈X or x∊X to denote that x is element if X; (2) The ∈ (∊) sign derives from Greek epsilon (specifically from its lunate form). Are there any doubts? Sasha1024 (talk) 19:34, 18 September 2020 (UTC)Reply

The main issue was that the Halmos text was being used as a source of a statement that it didn't support. There are a lot of formatting errors too, but those are fixable. In any case, if it's mainly a statement about the "element of" symbol, then it's not so much about the letter epsilon itself. –Deacon Vorbis (carbon • videos) 19:48, 18 September 2020 (UTC)Reply

Deacon Vorbis, ”the main issue was that the Halmos text was being used” — I am sorry, but what Halmos text are you talking about? There is no reference to any Halmos text in my proposed change. And I consider the statement about the "element of" symbol to be very related, because the "element of" symbol derives from epsilon. Sasha1024 (talk) 13:03, 22 October 2020 (UTC)Reply

Apparently someone else added a source to your addition. The source that was added didn't support what you wrote, which was unsourced, so it would need a source to be added at all. –Deacon Vorbis (carbon • videos) 13:21, 22 October 2020 (UTC)Reply

Source for what exactly: for (a) the fact that ∈ (or ∊) is nowadays used as "is element of" or for (b) the fact that nowaday ∈ (and ∊) derives from lunate epsilon? (I thought both are obvious, but maybe can provide sources for both of them.) (BTW, did you notice that no entries in that list contain sources?) Sasha1024 (talk) 10:49, 23 October 2020 (UTC) Pinging Deacon Vorbis. Sasha1024 (talk) 08:32, 26 October 2020 (UTC)Reply

Article specifies 2 different pronunciations (US, UK) citing Oxford English Dictionary for the UK variant. However, following the citation link confirms the US pronunciation while it does not confirm the UK variant provided in the article. The US variant matches the original Greek while the UK variant seems to be unsupported. 192.234.149.250 (talk) 17:18, 9 May 2025 (UTC)Reply

Agreed. If somebody can write IPA in Wikipedia style, this page at the OED says /ˈɛpsᵻlɒn/ and /ˈɛpsᵻlən/. --𝕁𝕄𝔽 (talk) 22:39, 10 May 2025 (UTC)Reply

Ten years later, this still seems to be an issue. Before we go deleting one at random, we really need to ask WP:WikiProject Greece about the distinction between

• U+03B5 ε GREEK SMALL LETTER EPSILON
• U+03F5 ϵ GREEK LUNATE EPSILON SYMBOL

Ok? 𝕁𝕄𝔽 (talk) 23:07, 21 October 2025 (UTC)Reply

No need to bother wikiprojects about that; I see no reason why we wouldn't be able to resolve this on talk based on our sources the normal way. My issue is that the existence of the different glyph forms and the existence of the separate mathematical symbol codepoint are two separate and partly independent issues, and for both practical and conceptual reasons we shouldn't use the one to illustrate the other. With the text you restored here [1], there are two main problems, one factual and one practical. First, the article is now again saying that the reverse-3 glyph is encoded U+03B5 ε GREEK SMALL LETTER EPSILON. That is just factually incorrect. U+03B5 doesn't encode the reverse-3 glyph; it encodes the letter as a textual character in whatever glyph shape a font designer chooses – it might just as well be the lunate glyph (as happens for instance in fonts of the "Porson" tradition, or in the "Olga" or "Galatea" fonts of Greek Font Society [2]), or any other. U+03F5 is designated for a specific glyph shape; U+03B5 isn't. That leads to the second problem: if you use the two codepoints to show the user the two glyph shapes, as we are now again doing in the intro sentence (lowercase ε or ϵ), we cannot be certain what our reader will see. Depending on what fonts they have, they might end up seeing the same lunate glyph twice. As a matter of principle, Wikipedia articles should never make assumptions about what fonts they are going to be displayed in – somebody might legitimately re-use this article in a print publication where all Latin text is in serif fonts and all Greek text is in Porson by default, and the text must then still make sense. This is why if you need to show the reader something about glyph variants below the character level, the only safe way of doing that is through graphics.

We may also ask if it is really necessary to present the glyph difference right in the very first sentence of the lead (given that it will be discussed extensively a bit further down the lead paragraph anyway). While the distinction between the two glyphs may be significant in the mathematical symbol context, for the letter itself as a textual character it is no more significant than that between double-storey and single-storey "a" or "g" in Latin, or latin "Q" with its differently styled tails.

As a minor point, the encoding of the characters in that lead sentence as it is now, using the mathematical symbol char enclosed in {{lang|el|ϵ}}, is conceptually wrong: since U+03F5 is designed exclusively for use as a mathematical symbol, it should never occur in text marked up as being in the Greek language. The epsilon used in Greek language text is, by definition, U+03B5.

- Fut.Perf. ☼ 08:15, 22 October 2025 (UTC)Reply

That satisfies my concern, thank you. But the solution needs more that just deleting it from the opening sentence and leaving everything else. I think you just volunteered to rewrite the lead . At present, far too much of it is taken up by a detailed description of mathematical usage that belongs in the body.

Yes,your point about U+0067 g LATIN SMALL LETTER G being represented equally by g or g is certainly true (lowercase L is a better example). Do we know of any routinely used modern Greek typefaces (i.e, not display typefaces) that use the lunate epsilon? 𝕁𝕄𝔽 (talk) 11:34, 22 October 2025 (UTC)Reply

The ones I mentioned above were the ones that I could quickly find. Porson (typeface) is probably the most prominent in print, having been the characteristic typeface of Oxford Classical Texts. I don't know how much of it is found in present-day printing. I'll admit that among common electronic fonts likely to be used on screen, those that use the 3-glyph are probably the large majority. About rewriting the lead, I tried to fix at least the two sentenced dealing with this specific issue in my previous edit, but I agree it would probably be better if a lot of this stuff were moved down into the body. Fut.Perf. ☼ 12:23, 22 October 2025 (UTC)Reply