Difference between revisions of "Morita invariants"

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* Number of isomorphism classes of simple modules
 
* Number of isomorphism classes of simple modules
* Isomorphism type of centre of algebra, and so dimension of centre
+
* Isomorphism type of centre of algebra, and so dimension of centre (hence, in the case of <math>k</math>-blocks of finite groups, the number of irreducible characters associated to the corresponding <math>\mathcal{O}</math>-block)
 
* Loewy structure and socle structure
 
* Loewy structure and socle structure
  
 
== Invariants preserved under <math>k</math>-Morita equivalence of blocks of finite groups ==
 
== Invariants preserved under <math>k</math>-Morita equivalence of blocks of finite groups ==
  
 +
* Invariants listed above
 
* Cartan matrix, up to rearrangement of rows and columns
 
* Cartan matrix, up to rearrangement of rows and columns
 
* Order of defect group
 
* Order of defect group
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== Invariants preserved under <math>\mathcal{O}</math>-Morita equivalence of blocks of finite groups ==
 
== Invariants preserved under <math>\mathcal{O}</math>-Morita equivalence of blocks of finite groups ==
 +
 +
* Invariants listed above
 +
* Number <math>k_h(B)</math> of irreducible characters of a given [[Glossary#Height of an irreducible character|height]] <math>h</math>
 +
* Decomposition matrix, up to rearrangement of rows and columns
  
 
== Invariants preserved under basic Morita equivalence of blocks of finite groups<ref>Note that by [[References#K|[KL18]]], if <math>k</math>-blocks are basic Morita equivalent, then the corresponding <math>\mathcal{O}</math>-blocks are Morita equivalent</ref> ==
 
== Invariants preserved under basic Morita equivalence of blocks of finite groups<ref>Note that by [[References#K|[KL18]]], if <math>k</math>-blocks are basic Morita equivalent, then the corresponding <math>\mathcal{O}</math>-blocks are Morita equivalent</ref> ==
 +
 +
* Invariants listed above
 +
* Isomorphism type of a defect group<ref>See Corollary 3.6 of [[References#P|[Pu99]]]</ref>
 +
* [[Glossary#Fusion system|Fusion system]] of the block<ref>See Corollary 3.6 of [[References#P|[Pu99]]]</ref>
  
 
== Invariants preserved under splendid Morita equivalence of blocks of finite groups ==
 
== Invariants preserved under splendid Morita equivalence of blocks of finite groups ==
 +
 +
* Invariants listed above
 +
* [[Glossary#Source algebra|Source algebra]]
  
 
== Notes ==
 
== Notes ==
  
 
<references />
 
<references />

Latest revision as of 11:40, 2 May 2024

Under-construction.png

Invariants preserved under Morita equivalence of blocks of f.d. [math]k[/math]-algebras

  • Number of isomorphism classes of simple modules
  • Isomorphism type of centre of algebra, and so dimension of centre (hence, in the case of [math]k[/math]-blocks of finite groups, the number of irreducible characters associated to the corresponding [math]\mathcal{O}[/math]-block)
  • Loewy structure and socle structure

Invariants preserved under [math]k[/math]-Morita equivalence of blocks of finite groups

  • Invariants listed above
  • Cartan matrix, up to rearrangement of rows and columns
  • Order of defect group
  • Exponent of defect group[1]
  • [math]p[/math]-rank of defect group[2]

Invariants preserved under [math]\mathcal{O}[/math]-Morita equivalence of blocks of finite groups

  • Invariants listed above
  • Number [math]k_h(B)[/math] of irreducible characters of a given height [math]h[/math]
  • Decomposition matrix, up to rearrangement of rows and columns

Invariants preserved under basic Morita equivalence of blocks of finite groups[3]

Invariants preserved under splendid Morita equivalence of blocks of finite groups

Notes

  1. See (78) of [Ku91]
  2. See Corollary 4 of [AE81], attributed to Donovan
  3. Note that by [KL18], if [math]k[/math]-blocks are basic Morita equivalent, then the corresponding [math]\mathcal{O}[/math]-blocks are Morita equivalent
  4. See Corollary 3.6 of [Pu99]
  5. See Corollary 3.6 of [Pu99]