# Talk:Lacunary sequence

From Encyclopedia of Mathematics

Post $\TeX$ notes

- I replace the sequence notation $\{\cdot\}$ by the more usual $(\cdot)$, uncomment the
`\newcommand`

for`\seq`

at the start of the file to revert this - I'm not entirely sure about the MSC here, could someone check it?

--Jjg 22:04, 3 May 2012 (CEST)

- About MSC: problematic indeed; but I believe that 42A55 "Lacunary series of trigonometric and other functions; Riesz products" is naturally the secondary classification, since it gives the main motivation here.
- And maybe 11B05 "Density, gaps, topology" rather than just 11Bxx? Indeed, lacunary sequences are somehow of very small density, with many large gaps. --Boris Tsirelson 22:31, 3 May 2012 (CEST)
- Agreed, thanks Boris --Jjg 23:41, 3 May 2012 (CEST)

- Shouldn't the notation $\lfloor\cdot\rfloor$ be used for the integer part? Or $\lceil\cdot\rceil$ (I never remember)? -- Sergei Yakovenko 07:16, 4 May 2012 (CEST)
- Convention seems to differ between $\lfloor\cdot\rfloor$ and $[\cdot]$ -- the former is favoured by combinatorics, the latter by number theory and analysis. TBloom 07:43, 4 May 2012 (CEST)
- As I remember, $\lfloor\cdot\rfloor$ rounds down $\lceil\cdot\rceil$ rounds up, and $[\cdot]$ rounds towards zero, so $\lfloor\cdot\rfloor$ and $[\cdot]$ are the same for positive numbers --Jjg 10:40, 4 May 2012 (CEST)

- Definition style changed according to Talk:EoM:This_project#Style_of_title_and_definition. --Ulf Rehmann 10:28, 4 May 2012 (CEST)
- But "A lacunary ..." rather that "The lacunary ...", surely? --Jjg 10:40, 4 May 2012 (CEST)

**How to Cite This Entry:**

Lacunary sequence.

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Lacunary_sequence&oldid=25924