Alphabeta Math

Euler-Twisted Hall Products, Green Coproducts, and Quantum Groups

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✓ 15 results · all verified · 0 also independently AI-judged
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1 · Prerequisites
Abstract Algebra
Algebraic Geometry
Braid Groups
Categorification and Geometric Representation Theory
Category Theory
Combinatorics
Commutative Algebra
Coxeter Groups
Functional Analysis
Homological Algebra
Lie Theory
Linear Algebra
Number Theory
Real Analysis
Set Theory
Topology
2 · Logical flowchart

3 · Items

Definition

The Hall-normalized extended positive Borel of a loopless quiver

Lemma

A symmetric Gaussian alternating sum vanishes in the Serre range

Lemma

A zero Yoneda splice factors through the middle object

Lemma

Low-degree exact sequences for Yoneda Ext in both variables

Definition

Finite-field hereditary Hall categories

Lemma

Finite-dimensional representations of an acyclic quiver form a hereditary finitary Hall category

Lemma

Finite loopless quiver nilpotent representation categories are hereditary and finitary

Lemma

The hereditary Euler form is additive on the Grothendieck group

Lemma

Exact-sequence counts equal endpoint automorphism counts times subobject counts

Definition

The Euler-twisted Hall algebra

Lemma

The Euler-twisted Hall product is well-defined

Definition

The Green Hall completion and coproduct

Lemma

The Euler-twisted Hall product is associative and unital

Lemma

Green coproduct coefficients are finite

Lemma

The Green cross–square counting identity

Definition

The extended Hall algebra and composition subalgebra

Lemma

The extended Hall torus action is well-defined

Lemma

The Green Hall coproduct is coassociative

Lemma

Products of Green coproducts converge coefficientwise

Theorem

Green’s coproduct is an algebra map into the twisted tensor completion

Proposition

The Green Hall pairing is nondegenerate and adjoint to product and coproduct

Corollary

The extended Green coproduct is an algebra map

Lemma

The extended Green and repository Drinfeld–Jimbo coproduct conventions agree on simple generators

Proposition

The Ringel assignment is a bialgebra homomorphism onto the extended composition subalgebra

Theorem

Prime-power specializations of the integral quantum half have a nondegenerate Green form

Lemma

Finite Serre word forms descend and have classical PBW rank bounds

Lemma

Green positivity specializes the integral half into the composition algebra

Lemma

Reflection classifies finite-Dynkin quiver indecomposables over a finite field

Lemma

Finite-Dynkin Hall algebras are generated by vertex simples

Lemma

Finite-field descent and restriction of Schur quiver representations

Lemma

Explicit affine D and E flag families give exponentially many indecomposables

Lemma

The full Hall algebra is simple-generated exactly in componentwise finite Dynkin type

Lemma

Rank-one skew kernels in a numerical quantum Serre algebra

Lemma

The nondegenerate integral specialization has a quantum Casimir

Lemma

A minimal numerical Serre kernel obeys the quantum Casimir constraint

Theorem

The prime-power numerical Serre half is the integral specialization

Theorem

The Ringel map embeds the extended positive Borel and is full Hall exactly in finite Dynkin type

Sources