Theorems · Theorem · combinatorics
Matrix.IsHadamard.four_dvd_card
∀ {n : Type u_2} [inst : Fintype n] [inst_1 : DecidableEq n] {A : Matrix n n ℤ},
A.IsHadamard → 2 < Fintype.card n → 4 ∣ Fintype.card nAn integer Hadamard matrix of order greater than two has order divisible by four. This is the standard divisibility obstruction in [Section 2.3][deLauneyFlannery2011].
- Cited by
- 0 results in Mathlib
- Foundations
- Depth 73 from the axioms · uses propext, Classical.choice, Quot.sound
- Assumes
- FintypeDecidableEq
Around this declaration
Dashed lines are statement dependencies; solid lines are citations in proofs.
Cites23
Mathlib declarations this one mentions in its statement or cites explicitly in its proof. Plumbing is filtered out.
- Fintypestatement and proof · cited by 7,736
- Finset.sumproof · cited by 5,195
- Matrixstatement and proof · cited by 4,303
- mul_oneproof · cited by 3,885
- Finset.univproof · cited by 3,473
- add_zeroproof · cited by 2,707
- Finset.sum_congrproof · cited by 2,323
- MulZeroClass.mul_zeroproof · cited by 2,091
- MulZeroClass.zero_mulproof · cited by 1,625
- Fintype.cardstatement and proof · cited by 1,386
- neg_negproof · cited by 960
- mul_negproof · cited by 590
Cited by0
Results whose statement or proof uses this declaration.
Nothing cites this yet.