Set notation for ACL matrix This might not be a computer science specific question and apologies if that is the case but it does come from material related to working out access control lists and I cannot understand the notation and I wonder if someone could break it down for me?
$$A’[s_i,o_j]=A[s_i,o_j] \; ∀(s_i,o_j)≄(s,o)$$
I understand that $A’[s_i,o_j]$ is the new resulting matrix after some operation and I think $s_i$ and $o_j$ are the matrix pairs that are not being amended although I do not know exactly that this is the case or how adding the $i$ and $j$ denotes this.
This might be way off the mark but is it saying that the new matrix is equal to the old matrix where none of the pairs are equal to the pair being deleted?
I am also looking at a list of set symbols and I cannot find this $≄$ listed.
The notation means:

For any $(s_i,o_j) \neq (s,o)$, $A'[s_i,o_j] = A[s_i,o_j]$.

The correct symbol seems to be $\neq$, &quot;not equal&quot;, rather than what you wrote.
The symbol $\forall$ means &quot;for all&quot;.
The notation $s_i$ just means &quot;element number $i$ in the set of rows&quot;, and $o_j$ is similarly &quot;element number $j$ in the set of columns&quot;. You could just as well have replaced $s_i,o_j$ with any two other symbols (other than $s,o$).