The graded first-arrow sequence of Π(Δ) #
periodic-mesh-calculations.tex (proof of the bound by the U_d): "The
first-arrow presentation of each simple gives, as in (A.1), an exact sequence
e_iΠ⟨2⟩ → ⊕_{j∼i} e_jΠ⟨1⟩ → e_iΠ → S_i → 0. Exactness at the middle term is
proved as for (A.1)."
We fix the endpoint j and the degree. Write h_i(d) = dim e_i Π_d e_j. The
middle exactness (exact_star, proved for Proposition 4.1) and the grading of
the ideal give ∑_{l∼i} h_l(d+1) ≤ h_i(d+2) + h_i(d) and
∑_{l∼i} h_l(0) ≤ h_i(1); these are the inequalities κ ≥ 0 of UBound.
The ideal of Π(Δ) between two vertices.
Instances For
Middle exactness with a fixed endpoint.
Degree projections #
The ideal of Π(Δ) is graded.
The graded pieces e_i Π_d e_j #
e_i Π_d e_j, inside kQ(i, j) modulo the ideal.
Instances For
Prefixing an arrow, on kQ(·, j).
Instances For
Prefixing an arrow, on e_l Π e_j → e_i Π e_j.
Instances For
⊕_{l∼i} e_l Π_d e_j → e_i Π_{d+1} e_j.
Instances For
e_i Π_d e_j → ⊕_{l∼i} e_l Π_{d+1} e_j, with the signs of the relation.
Instances For
Middle exactness in each degree.
The dimension inequalities ∑_{l∼i} h_l(d+1) ≤ h_i(d+2) + h_i(d).
A nonzero graded piece contains a path outside the ideal.
The adjacency matrix of Δ.
Instances For
The lower bound (dim e_i Π_N e_j)_{ij} ≥ U_N when U_0, …, U_N ≥ 0
(periodic-mesh-calculations.tex).