# Fibrifold

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{{inline |date=May 2024}}
In mathematics, a  '''fibrifold''' is (roughly) a [fiber space](/source/fiber_space) whose fibers and base spaces are [orbifold](/source/orbifold)s. They were introduced by {{harvs | txt| last1=Conway | first1=John Horton | author1-link=John Horton Conway | last2=Delgado Friedrichs | first2=Olaf | last3=Huson | first3=Daniel H. | last4=Thurston | first4=William P. | author4-link=William Thurston | title=On three-dimensional space groups | url=http://www.emis.de/journals/BAG/vol.42/no.2/17.html | mr=1865535  | year=2001 | journal=Beiträge zur Algebra und Geometrie | issn=0138-4821 | volume=42 | issue=2 | pages=475–507}}, who introduced a system of notation for 3-dimensional fibrifolds and used this  to assign names to the 219 affine [space group](/source/space_group) types. 184 of these are considered reducible, and 35 irreducible.

== Irreducible cubic space groups ==
[[File:35 cubic fibrifold groups.svg|320px|thumb|The 35/36 irreducible [cubic space group](/source/cubic_space_group)s in fibrifold and international index and [Hermann–Mauguin notation](/source/Hermann%E2%80%93Mauguin_notation). 212 and 213 are enantiomorphous pairs giving the same fibrifold notation.]]
The 35 irreducible space groups correspond to the [cubic space group](/source/cubic_space_group).
{| class=wikitable
|+ 35 irreducible space groups
|-
|8<sup>o</sup>:2||4<sup>−</sup>:2||4<sup>o</sup>:2||4<sup>+</sup>:2||2<sup>−</sup>:2||2<sup>o</sup>:2||2<sup>+</sup>:2||1<sup>o</sup>:2
|-
|8<sup>o</sup>||4<sup>−</sup>||4<sup>o</sup>||4<sup>+</sup>||2<sup>−</sup>||2<sup>o</sup>||2<sup>+</sup>||1<sup>o</sup>
|-
|8<sup>o</sup>/4||4<sup>−</sup>/4||4<sup>o</sup>/4||4<sup>+</sup>/4||2<sup>−</sup>/4||2<sup>o</sup>/4||2<sup>+</sup>/4||1<sup>o</sup>/4
|-
|8<sup>−o</sup>||8<sup>oo</sup>||8<sup>+o</sup> ||4<sup>− −</sup>||4<sup>−o</sup>||4<sup>oo</sup>||4<sup>+o</sup>||4<sup>++</sup>||2<sup>−o</sup>||2<sup>oo</sup>||2<sup>+o</sup>
|}

{| class=wikitable
|+ 36 cubic groups
|-
!Class<BR>Point group
!Hexoctahedral<BR>*432 (m{{overline|3}}m)
!Hextetrahedral<BR>*332 ({{overline|4}}3m)
!Gyroidal<BR>432 (432)
!Diploidal<BR>3*2 (m{{overline|3}})
!Tetartoidal<BR>332 (23)
|- align=center
!bc lattice (I)
|8<sup>o</sup>:2 (Im{{overline|3}}m)
|4<sup>o</sup>:2 (I{{overline|4}}3m)
|8<sup>+o</sup> (I432)
|8<sup>−o</sup> (I{{overline|3}})
|4<sup>oo</sup> (I23)
|- align=center
!rowspan=2|nc lattice (P)
|4<sup>−</sup>:2 (Pm{{overline|3}}m)
|rowspan=2|2<sup>o</sup>:2 (P{{overline|4}}3m)
|4<sup>−o</sup> (P432)
|4<sup>−</sup> (Pm{{overline|3}})
|rowspan=2|2<sup>o</sup> (P23)
|- align=center
|4<sup>+</sup>:2 (Pn{{overline|3}}m)
|4<sup>+</sup> (P4<sub>2</sub>32)
|4<sup>+o</sup> (Pn{{overline|3}})
|- align=center
!rowspan=2|fc lattice (F)
|2<sup>−</sup>:2 (Fm{{overline|3}}m)
|rowspan=2|1<sup>o</sup>:2 (F{{overline|4}}3m)
|2<sup>−o</sup> (F432)
|2<sup>−</sup> (Fm{{overline|3}})
|rowspan=2|1<sup>o</sup> (F23)
|- align=center
|2<sup>+</sup>:2 (Fd{{overline|3}}m)
|2<sup>+</sup> (F4<sub>1</sub>32)
|2<sup>+o</sup> (Fd{{overline|3}})
|- align=center valign=top
!Other<BR>lattice<BR>groups
|8<sup>o</sup> (Pm{{overline|3}}n)<BR>8<sup>oo</sup> (Pn{{overline|3}}n)<BR>4<sup>− −</sup> (Fm{{overline|3}}c)<BR>4<sup>++</sup> (Fd{{overline|3}}c)
|4<sup>o</sup> (P{{overline|4}}3n)<BR>2<sup>oo</sup> (F{{overline|4}}3c)
|
|
|
|- align=center valign=top
!Achiral<BR>quarter<BR>groups
|8<sup>o</sup>/4 (Ia{{overline|3}}d)
|4<sup>o</sup>/4 (I{{overline|4}}3d)
|4<sup>+</sup>/4 (I4<sub>1</sub>32)<BR>2<sup>+</sup>/4 (P4<sub>3</sub>32,<BR>P4<sub>1</sub>32)
|2<sup>−</sup>/4 (Pa{{overline|3}})<BR>4<sup>−</sup>/4 (Ia{{overline|3}})
|1<sup>o</sup>/4 (P2<sub>1</sub>3)<BR>2<sup>o</sup>/4 (I2<sub>1</sub>3)
|}

{| class=wikitable width=580
|280px
|180px
|240px
|- valign=top
|8 primary hexoctahedral hextetrahedral lattices of the cubic space groups
|colspan=2|The fibrifold cubic subgroup structure shown is based on extending symmetry of the [tetragonal disphenoid](/source/tetragonal_disphenoid) fundamental domain of space group 216, similar to the [square](/source/square)
|}

Irreducible group symbols (indexed 195−230) in [Hermann–Mauguin notation](/source/Hermann%E2%80%93Mauguin_notation), Fibrifold notation, geometric notation, and [Coxeter notation](/source/Coxeter_notation):
{| class=wikitable
|-
!Class<br>([Orbifold](/source/Orbifold_notation) point group)
!colspan=10| [Space group](/source/Space_group)s
|-align=center
!rowspan=5|Tetartoidal<BR>23<br>(332)
!195||196||197||198||199 || colspan=5|&nbsp;
|- BGCOLOR="#ffe0e0" align=center
| P23 || F23 || I23 || P2<sub>1</sub>3 || I2<sub>1</sub>3 || colspan=5|&nbsp;
|- BGCOLOR="#e0e0ff" align=center
|2<sup>o</sup>||1<sup>o</sup>||4<sup>oo</sup>||1<sup>o</sup>/4||2<sup>o</sup>/4 || colspan=5|&nbsp;
|- BGCOLOR="#ffffd0" align=center
| P{{overline|3}}.{{overline|3}}.{{overline|2}} || F{{overline|3}}.{{overline|3}}.{{overline|2}} || I{{overline|3}}.{{overline|3}}.{{overline|2}} || P{{overline|3}}.{{overline|3}}.{{overline|2}}<sub>1</sub> || I{{overline|3}}.{{overline|3}}.{{overline|2}}<sub>1</sub> || colspan=5|&nbsp;
|- BGCOLOR="#e0ffe0" align=center
| [(4,3<sup>+</sup>,4,2<sup>+</sup>)] || [3<sup>[4]</sup>]<sup>+</sup>|| [(4,3<sup>+</sup>,4,2<sup>+</sup>)](/source/(4%2C3%3Csup%3E%2B%3C%2Fsup%3E%2C4%2C2%3Csup%3E%2B%3C%2Fsup%3E)) ||  || || colspan=5|&nbsp;
|- align=center
!rowspan=5|Diploidal<BR>{{overline|4}}3m<br>(3*2)
!200||201||202||203||204||205||206 ||colspan=3|&nbsp;
|- BGCOLOR="#ffe0e0"  align=center
| Pm{{overline|3}} || Pn{{overline|3}} || Fm{{overline|3}} || Fd{{overline|3}} || I{{overline|3}} || Pa{{overline|3}} || Ia{{overline|3}} ||colspan=3|&nbsp;
|- BGCOLOR="#e0e0ff" align=center
|4<sup>−</sup>||4<sup>+o</sup>||2<sup>−</sup>||2<sup>+o</sup>||8<sup>−o</sup>||2<sup>−</sup>/4||4<sup>−</sup>/4 ||colspan=3|&nbsp;
|- BGCOLOR="#ffffd0" align=center
| P4{{overline|3}} || P<sub>n</sub>4{{overline|3}} || F4{{overline|3}} || F<sub>d</sub>4{{overline|3}} || I4{{overline|3}} || P<sub>b</sub>4{{overline|3}} || I<sub>b</sub>4{{overline|3}} ||colspan=3|&nbsp;
|- BGCOLOR="#e0ffe0" align=center
|[4,3<sup>+</sup>,4]||<nowiki>[[</nowiki>4,3<sup>+</sup>,4]<sup>+</sup>] ||[4,(3<sup>1,1</sup>)<sup>+</sup>] ||<nowiki>[[</nowiki>3<sup>[4]</sup><nowiki>]]</nowiki><sup>+</sup> ||<nowiki>[</nowiki>4,3<sup>+</sup>,4<nowiki>](/source/%3C%2Fnowiki%3E4%2C3%3Csup%3E%2B%3C%2Fsup%3E%2C4%3Cnowiki%3E)</nowiki>|| || ||colspan=3|&nbsp;

|- align=center
!rowspan=5|Gyroidal<BR>432<br>(432)
!207||208||209||210||211||212||213||214||colspan=2|&nbsp;

|- BGCOLOR="#ffe0e0"  align=center
| P432 || P4<sub>2</sub>32 || F432 || F4<sub>1</sub>32 || I432 || P4<sub>3</sub>32||P4<sub>1</sub>32 || I4<sub>1</sub>32||colspan=2|&nbsp;
|- BGCOLOR="#e0e0ff" align=center
||4<sup>−o</sup>||4<sup>+</sup>||2<sup>−o</sup>||2<sup>+</sup>||8<sup>+o</sup>||colspan=2|2<sup>+</sup>/4||4<sup>+</sup>/4||colspan=2|&nbsp;

|- BGCOLOR="#ffffd0" align=center
| P{{overline|4}}.{{overline|3}}.{{overline|2}} || P{{overline|4}}<sub>2</sub>.{{overline|3}}.{{overline|2}} || F{{overline|4}}.{{overline|3}}.{{overline|2}} || F{{overline|4}}<sub>1</sub>.{{overline|3}}.{{overline|2}} || I{{overline|4}}.{{overline|3}}.{{overline|2}} || P{{overline|4}}<sub>3</sub>.{{overline|3}}.{{overline|2}} || P{{overline|4}}<sub>1</sub>.{{overline|3}}.{{overline|2}} || I{{overline|4}}<sub>1</sub>.{{overline|3}}.{{overline|2}} ||colspan=2|&nbsp;
|- BGCOLOR="#e0ffe0" align=center
|[4,3,4]<sup>+</sup> ||<nowiki>[[</nowiki>4,3,4]<sup>+</sup>]<sup>+</sup> ||[4,3<sup>1,1</sup>]<sup>+</sup> ||<nowiki>[[</nowiki>3<sup>[4]</sup><nowiki>]]</nowiki><sup>+</sup>  ||<nowiki>[</nowiki>4,3,4<nowiki>](/source/%3C%2Fnowiki%3E4%2C3%2C4%3Cnowiki%3E)</nowiki><sup>+</sup> || colspan=2| || ||colspan=2|&nbsp;
|- align=center
!rowspan=5|Hextetrahedral<BR>{{overline|4}}3m<br>(*332)
!215||216||217||218||219||220|| colspan=4|&nbsp;
|- BGCOLOR="#ffe0e0"  align=center
| P{{overline|4}}3m || F{{overline|4}}3m || I{{overline|4}}3m || P{{overline|4}}3n || F{{overline|4}}3c || I{{overline|4}}3d || colspan=4|&nbsp;
|- BGCOLOR="#e0e0ff" align=center
||2<sup>o</sup>:2||1<sup>o</sup>:2||4<sup>o</sup>:2||4<sup>o</sup>||2<sup>oo</sup>||4<sup>o</sup>/4|| colspan=4|&nbsp;

|- BGCOLOR="#ffffd0" align=center
|| P33 || F33 || I33 || P<sub>n</sub>3<sub>n</sub>3<sub>n</sub> || F<sub>c</sub>3<sub>c</sub>3<sub>a</sub>|| I<sub>d</sub>3<sub>d</sub>3<sub>d</sub> || colspan=4|&nbsp;
|- BGCOLOR="#e0ffe0" align=center
|[(4,3,4,2<sup>+</sup>)] || [3<sup>[4]</sup>] || <nowiki>[</nowiki>(4,3,4,2<sup>+</sup>)<nowiki>](/source/%3C%2Fnowiki%3E(4%2C3%2C4%2C2%3Csup%3E%2B%3C%2Fsup%3E)%3Cnowiki%3E)</nowiki> ||<nowiki>[[</nowiki>(4,3,4,2<sup>+</sup>)]<sup>+</sup>] ||[<sup>+</sup>(4,{3),4}<sup>+</sup>] || || colspan=4|&nbsp;

|- align=center
!rowspan=5|Hexoctahedral<BR>m{{overline|3}}m<br>(*432)
!221||222||223||224||225||226||227||228||229||230
|- BGCOLOR="#ffe0e0"  align=center
| Pm{{overline|3}}m || Pn{{overline|3}}n || Pm{{overline|3}}n || Pn{{overline|3}}m || Fm{{overline|3}}m || Fm{{overline|3}}c || Fd{{overline|3}}m || Fd{{overline|3}}c || Im{{overline|3}}m || Ia{{overline|3}}d
|- BGCOLOR="#e0e0ff" align=center
||4<sup>−</sup>:2||8<sup>oo</sup>||8<sup>o</sup> ||4<sup>+</sup>:2||2<sup>−</sup>:2||4<sup>−−</sup> ||2<sup>+</sup>:2||4<sup>++</sup> ||8<sup>o</sup>:2||8<sup>o</sup>/4
|- BGCOLOR="#ffffd0" align=center
|| P43 || P<sub>n</sub>4<sub>n</sub>3<sub>n</sub> || P4<sub>n</sub>3<sub>n</sub> || P<sub>n</sub>43 || F43 || F4<sub>c</sub>3<sub>a</sub> || F<sub>d</sub>4<sub>n</sub>3 || F<sub>d</sub>4<sub>c</sub>3<sub>a</sub> || I43 || I<sub>b</sub>4<sub>d</sub>3<sub>d</sub>
|- BGCOLOR="#e0ffe0" align=center
||[4,3,4]|| ||<nowiki>[[</nowiki>4,3,4]<sup>+</sup>] ||[(4<sup>+</sup>,2<sup>+</sup>)[3<sup>[4]</sup><nowiki>]]</nowiki> ||[4,3<sup>1,1</sup>] ||[4,(3,4)<sup>+</sup>] ||<nowiki>[[</nowiki>3<sup>[4]</sup><nowiki>]]</nowiki> ||<nowiki>[</nowiki><sup>+</sup>(4,{3),4}<sup>+</sup><nowiki>](/source/%3C%2Fnowiki%3E%3Csup%3E%2B%3C%2Fsup%3E(4%2C%7B3)%2C4%7D%3Csup%3E%2B%3C%2Fsup%3E%3Cnowiki%3E)</nowiki> || <nowiki>[</nowiki>4,3,4<nowiki>](/source/%3C%2Fnowiki%3E4%2C3%2C4%3Cnowiki%3E)</nowiki> ||
|}

==References==
{{refbegin}}
*{{Citation | last1=Conway | first1=John Horton | author1-link=John Horton Conway | last2=Delgado Friedrichs | first2=Olaf | last3=Huson | first3=Daniel H. | last4=Thurston | first4=William P. | author4-link=William Thurston | title=On three-dimensional space groups | url=http://www.emis.de/journals/BAG/vol.42/no.2/17.html | mr=1865535  | year=2001 | journal=Beiträge zur Algebra und Geometrie | issn=0138-4821 | volume=42 | issue=2 | pages=475–507}}
*{{citation |first1=David |last1=Hestenes |first2=Jeremy W. |last2=Holt |title=The Crystallographic Space Groups in Geometric Algebra |journal=Journal of Mathematical Physics |volume=48 |issue=2 |pages=023514 |date=February 2007 |doi=10.1063/1.2426416 |bibcode=2007JMP....48b3514H |url=https://davidhestenes.net/geocalc/pdf/CrystalGA.pdf }}
*{{citation |first1=John H. |last1=Conway |first2=Heidi |last2=Burgiel |first3=Chaim |last3=Goodman-Strauss |title=The Symmetries of Things |publisher=Taylor & Francis |year=2008 |isbn=978-1-56881-220-5 |zbl=1173.00001}}
*{{citation |first=H.S.M. |last=Coxeter |author-link=H. S. M. Coxeter |chapter=Regular and Semi Regular Polytopes III |chapter-url=https://books.google.com/books?id=fUm5Mwfx8rAC&pg=PA313 |editor-first=F. Arthur |editor-last=Sherk |editor-first2=Peter |editor2-last=McMullen |editor3-first=Anthony C. |editor3-last=Thompson |editor4-first=Asia Ivić |display-editors=3 |editor4-last=Weiss |title=Kaleidoscopes: Selected Writings of H.S.M. Coxeter |publisher=Wiley |year=1995 |isbn=978-0-471-01003-6 |pages=[https://archive.org/details/kaleidoscopessel0000coxe/page/313 313–358] |zbl=0976.01023 |url=https://archive.org/details/kaleidoscopessel0000coxe/page/313 }}
{{refend}}

Category:Symmetry
Category:Finite groups
Category:Discrete groups

{{geometry-stub}}

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Adapted from the Wikipedia article [Fibrifold](https://en.wikipedia.org/wiki/Fibrifold) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Fibrifold?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.
