Is it good style to write $0, $0
The following does not seem so clear:
$0
as it may be interpreted as: $0 and $ j<1$ or $0, $0
Is it good style to write $0, $0
The following does not seem so clear:
$0
as it may be interpreted as: $0 and $ j<1$ or $0, $0
It depends on context.
Let $0\le a$, $b\le 0$ and $c = a - b$. Then $0\le c$.
You can use an interval instead: $i,j,k\in (0,1)$.
It is okay. The comma indicates that there is no necessary relation between $i,j$ and $k$.
I would definitely interpret $0 < i,j < 1$ as $0 < i < 1 \text{ and } 0 < j < 1. \quad (*)$ I would not interpret it as $0 < i \text{ and } j < 1. \quad (**)$ It is conventional, when writing a single inequality between a variable and a constant, to put the variable on the left, so if I meant (**), I would write $i > 0,\, j < 1.$