Wikipedia:Reference desk/Archives/Mathematics/2023 August 17

= August 17 =

What does this symbol mean?
I encountered {n}2 in a paper in number theory. I couldn't find it in Glossary of mathematical symbols or List of mathematical symbols by subject, but from the context, it seems to be "n mod 2". Is that right? Bubba73 You talkin' to me? 01:16, 17 August 2023 (UTC)
 * These lists are definitely incomplete. For example, neither these, nor any of the lists they refer to, mention the Schläfli symbols, which are a standardized notation. They are also incomplete as mathematicians may invent notation as they see fit. The notation $$[n]_m$$ for the equivalence class modulo $m$ of integer $n$ is not uncommon, but I don't think I saw $$\{n\}_2$$ with curly braces before. Whether it means what you think it means in the context in which you encountered it is impossible to tell without examining that context. --Lambiam 08:58, 17 August 2023 (UTC)


 * It is in conjecture 2.2 here: https://arxiv.org/pdf/1211.1588.pdf Bubba73 You talkin' to me? 18:26, 17 August 2023 (UTC)
 * The definition is given at the end of Section 1 on page 3 and seems to be in line with Lambiam's answer (not a field I'm familiar with; it makes sense when read as numbers but I don't quite see where classes come in). --Wrongfilter (talk) 20:47, 17 August 2023 (UTC
 * Thanks, I should not have skipped over that. Bubba73 You talkin' to me? 21:10, 17 August 2023 (UTC)


 * The definition of $$\{a\}_n$$ given there corresponds to what some programming languages denote as $$a\operatorname{mod}n.$$ For example, $$\{123\}_{16}=16\cdot\{123/16\}=16\cdot\{7.6875\}=16\cdot 0.6875=11.$$ --Lambiam 21:28, 17 August 2023 (UTC)


 * Thanks again. Bubba73 You talkin' to me? 00:43, 18 August 2023 (UTC)