8.21.3 Can you answer these questions?

8.21.3.1 Is it safe to name the local variables by ending with "$"?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=270153

In many cases I need to copy the  Global`  symbols  foo  into  Module/Block , and to memory the ... 
[scoping]
 

asked by Lilyric https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=86893 Score of 1

8.21.3.2 Solving a 2D recurrence diagonal-by-diagonal

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=269894

I have a 3D recurrence relation -- which I know can be hard for Mathematica to work with, so I boiled it down to 2D. 
We have two functions, $f_1(i,j)$, $f_2(i,j)$ defined on the state space $\{(i,j) | ... 
[recursion] [difference-equations] [boundary-conditions]
 

asked by black https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=86287 Score of 1

8.21.3.3 An error in the short form of a two-dimensional array?

https://mathematica.stackexchange.com/landing/r/digest?cta=question&id=270046

I noticed very strange behavior in the function Short when applied to a two-dimensional list of real numbers in Mathematica 12.3.  Consider that 
... 
[front-end] [array]
 

asked by Ed M. https://mathematica.stackexchange.com/landing/r/digest?cta=user&id=42279 Score of 1