update notations
This commit is contained in:
@@ -40,20 +40,20 @@ Let $G$ and $H$ be the generator and parity-check matrices of (any) linear code
|
||||
#### Lemma 1
|
||||
|
||||
$$
|
||||
H G^T = 0
|
||||
H G^\top = 0
|
||||
$$
|
||||
|
||||
<details>
|
||||
<summary>Proof</summary>
|
||||
|
||||
By definition of generator matrix and parity-check matrix, $forall e_i\in H$, $e_iG^T=0$.
|
||||
By definition of generator matrix and parity-check matrix, $forall e_i\in H$, $e_iG^\top=0$.
|
||||
|
||||
So $H G^T = 0$.
|
||||
So $H G^\top = 0$.
|
||||
</details>
|
||||
|
||||
#### Lemma 2
|
||||
|
||||
Any matrix $M\in \mathbb{F}_q^{(n-k)\times n}$ such that $\operatorname{rank}(M) = n - k$ and $M G^T = 0$ is a parity-check matrix for $C$ (i.e. $C = \ker M$).
|
||||
Any matrix $M\in \mathbb{F}_q^{(n-k)\times n}$ such that $\operatorname{rank}(M) = n - k$ and $M G^\top = 0$ is a parity-check matrix for $C$ (i.e. $C = \ker M$).
|
||||
|
||||
<details>
|
||||
<summary>Proof</summary>
|
||||
@@ -62,7 +62,7 @@ It is sufficient to show that the two statements
|
||||
|
||||
1. $\forall c\in C, c=uG, u\in \mathbb{F}^k$
|
||||
|
||||
$M c^T = M(uG)^T = M(G^T u^T) = 0$ since $M G^T = 0$.
|
||||
$M c^\top = M(uG)^\top = M(G^\top u^\top) = 0$ since $M G^\top = 0$.
|
||||
|
||||
Thus $C \subseteq \ker M$.
|
||||
|
||||
@@ -84,15 +84,15 @@ We proceed by applying the lemma 2.
|
||||
|
||||
1. $\operatorname{rank}(H) = n - k$ since $H$ is a Vandermonde matrix times a diagonal matrix with no zero entries, so $H$ is invertible.
|
||||
|
||||
2. $H G^T = 0$.
|
||||
2. $H G^\top = 0$.
|
||||
|
||||
note that $\forall$ row $i$ of $H$, $0\leq i\leq n-k-1$, $\forall$ column $j$ of $G^T$, $0\leq j\leq k-1$
|
||||
note that $\forall$ row $i$ of $H$, $0\leq i\leq n-k-1$, $\forall$ column $j$ of $G^\top$, $0\leq j\leq k-1$
|
||||
|
||||
So
|
||||
|
||||
$$
|
||||
\begin{aligned}
|
||||
H G^T &= \begin{bmatrix}
|
||||
H G^\top &= \begin{bmatrix}
|
||||
1 & 1 & \cdots & 1\\
|
||||
\alpha_1 & \alpha_2 & \cdots & \alpha_n\\
|
||||
\alpha_1^2 & \alpha_2^2 & \cdots & \alpha_n^2\\
|
||||
|
||||
Reference in New Issue
Block a user