Coset Enumeration: Difference between revisions

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== Problem Description==
{{DISPLAYTITLE:Coset Enumeration (Coset Enumeration)}}
== Description ==  


Coset enumeration programs implement systematic procedures for enumerating the cosets of a subgroup H of finite index in a group G, given a set of defining relations for G and words generating H.


== Bounds Chart ==
== Parameters ==  
[[File:Coset_EnumerationBoundsChart.png|350px]]


== Step Chart ==
$n$: number of generators
[[File:Coset_EnumerationStepChart.png|350px]]
 
$g$: order of group (possibly exponential in $n$)
 
$k$: number of relations
 
$c$: maximum number of generators multiplied together in a relation
 
== Table of Algorithms ==  
 
{| class="wikitable sortable"  style="text-align:center;" width="100%"
 
! Name !! Year !! Time !! Space !! Approximation Factor !! Model !! Reference


== Improvement Table ==
{| class="wikitable" style="text-align:center;" width="100%"
!width="20%" | Complexity Classes !! width="40%" | Algorithm Paper Links !! width="40%" | Lower Bounds Paper Links
|-
| rowspan="1" | Exp/Factorial
|
|
|-
|-
| rowspan="1" | Polynomial > 3
 
|
| [[Todd–Coxeter algorithm (Coset Enumeration Coset Enumeration)|Todd–Coxeter algorithm]] || 1936 || $O({2}^n)$ || $O(gkc)$ || Exact || Deterministic || [https://www.cambridge.org/core/journals/proceedings-of-the-edinburgh-mathematical-society/article/practical-method-for-enumerating-cosets-of-a-finite-abstract-group/0306574AD958F694A0A8339338348AA1 Time]
|
|-
|-
| rowspan="1" | Cubic
| [[Haselgrove-Leech-Trotter (HLT) algorithm (Coset Enumeration Coset Enumeration)|Haselgrove-Leech-Trotter (HLT) algorithm]] || 1940 || $O({2}^n)$ || $O(ng)$? || Exact || Deterministic || 
|
|
|-
|-
| rowspan="1" | Quadratic
| [[Knuth–Bendix algorithm (Coset Enumeration Coset Enumeration)|Knuth–Bendix algorithm]] || 1970 || $O({1.5}^n n^{2} logn)$ || $O(ng)$??? || Exact || Deterministic || [https://www.cs.tufts.edu/~nr/cs257/archive/don-knuth/knuth-bendix.pdf Time]
|
|
|-
|-
| rowspan="1" | nlogn
|}
|
 
|
== Time Complexity Graph ==
|-
 
| rowspan="1" | Linear
[[File:Coset Enumeration - Time.png|1000px]]
|
|
|-
| rowspan="1" | logn
|
|
|-|}

Latest revision as of 10:08, 28 April 2023

Description

Coset enumeration programs implement systematic procedures for enumerating the cosets of a subgroup H of finite index in a group G, given a set of defining relations for G and words generating H.

Parameters

$n$: number of generators

$g$: order of group (possibly exponential in $n$)

$k$: number of relations

$c$: maximum number of generators multiplied together in a relation

Table of Algorithms

Name Year Time Space Approximation Factor Model Reference
Todd–Coxeter algorithm 1936 $O({2}^n)$ $O(gkc)$ Exact Deterministic Time
Haselgrove-Leech-Trotter (HLT) algorithm 1940 $O({2}^n)$ $O(ng)$? Exact Deterministic
Knuth–Bendix algorithm 1970 $O({1.5}^n n^{2} logn)$ $O(ng)$??? Exact Deterministic Time

Time Complexity Graph

Coset Enumeration - Time.png