Acknowledgements
Introduction
1. Preliminaries and basic tools
1.1. Grothendieck group and Euler form
1.2. Dimension, multiplicity and Hilbert series
1.3. Algebras and modules
1.4. Graded algebras and modules
1.5. Artin-Schelter regular algebras
1.6. Three dimensional Artin-Schelter algebras
1.7. Filtered algebras and modules
2. Ideals of quadratic Artin-Schelter algebras
2.1. Motivation, main results and analogy
2.2. Hilbert schemes on affine planes
2.3. Hilbert schemes on projective planes
2.4. Stable vector bundles on the projective plane
2.5. From reflexive ideals to normalized line bundles
2.5.1. Torsion free and reflexive objects
2.5.2. The Grothendieck group and the Euler form for quantum planes
2.5.3. Normalized rank one objects
2.5.4. Cohomology of line bundles on quantum planes
2.5.5. Restriction of line bundles to the divisor
2.5.6. From line bundles to quiver representations
2.5.6.1. Generalized Beilinson equivalence
2.5.6.2. Point and line representations
2.5.6.3. First description of Rp(P2)
2.5.6.4. Line bundles on P2 with invariant one
2.5.6.5. Induced Kronecker quiver representations
2.5.6.7. Second description of Ry(P2) and proof of Theorem 1
2.5.6.8. Description of the varieties D for Sklyanin algebras and proof of Theorem 2
2.5.6.9. Filtrations of line bundles and proof of Theorem 3
3. Hilbert series of ideals of quadratic Artin-Schelter algebras
3.1. Introduction and main results
3.2. Notations and conventions
3.3. Proof that the conditions in Theorem 6 are necessary
3.4. Proof that the conditions in Theorem 6 are sufficient
3.5. Proof of other properties of Hilbert series
3.6. The stratification by Hilbert series
4. Modules of GK-dimension one over quadratic Artin-Schelter algebras
4.1. Proof of Theorem 7
5. Incidence between strata on the Hilbert scheme of points on the projective plane
5.1. Introduction and main result
5.2. Outline of the proof of the main theorem
5.3. Four sets of conditions
5.3.1. Translation of the length zero condition
5.3.2. Translation of the dimension condition
5.3.3. Translation of the tangent condition
5.4. Truncated point modules
5.5. A complex whose homology is J
5.6. The Hilbert scheme of an ideal
5.7. Estimating the dimension of Ext(J,J)
5.8. Tying things together
6. Ideals of cubic Artin-Schelter algebras
6.1. Introduction and main results
6.2. From reflexive ideals to normalized line bundles
6.2.1. Torsion free and reflexive objects
6.2.2. The Grothendieck group and the Euler form for quantum quadrics
6.2.3. Normalized rank one objects
6.2.4. Cohomology of line bundles on quantum quadrics
6.2.5. Hilbert series of ideals and proof of Theorem 14
6.2.6. Ideals of linear cubic Artin-Schelter algebras
6.2.7. Hilbert scheme of points
6.2.8. Some results on line and conic objects
6.2.9. Restriction of line bundles to the divisor C
6.2.10. From line bundles to quiver representations
6.2.10.1. Generalized Beilinson equivalence
6.2.10.2. Point, line and conic representations
6.2.10.3. First description of Rin
6.2.10.4. Line bundles on X with invariants (1,0) and (1,1)
6.2.10.5. Description of Rin,n)(X) for the enveloping algebra
6.2.10.6. Restriction to a full subquiver
6.2.10.8. Second description of Rin
6.2.10.9. Descriptions of the varieties for the enveloping algebra
6.2.11. Description of the varieties Din,n for generic type A
6.2.12. Filtrations of line bundles and proof of Theorem 12
6.2.13. Invariant ring of the first Weyl algebra and proof of Theorem 14
A Serre duality for graded rings
B Upper semi-continuity for noncommutative Proj
C Hilbert series of ideals with small invariants
C.1. Quadratic Artin-Schelter algebras
C.2. Cubic Artin-Schelter algebras
D A visual criterion for incidence problems of length zero
E Maple programs
E.1. Procedures for Chapter 3: Examples
E.2. Procedures for Chapter 5: Examples
E.3. Procedures for Chapter 3
E.4. Additional procedures for Chapter 5
F Hilbert graphs and combinatorics
F.1. Hilbert graphs and incidence problems for low invariants
F.2. General Hilbert graphs
G An inequality on broken chessboards
G.1. Partitions and chess Ferrers graphs
G.2. From partitions to Castelnuovo functions
G.3. Proof that the condition in Theorem A is necessary
G.4. Proof that the condition in Theorem A is sufficient
Bibliography