So I was trying to simplify some expression and it didn’t work for me and I couldn’t understand why. Boiling it down to its simplest form, if I use different letters of the alphabet sometimes it works and sometimes it doesn’t;. I give 5 examples to show it’s not even the order of the alphabet. I also go in an out of the Julia REPL each time to be sure previous attempts don’t influence the next. What am I doing wrong here?

```
% julia
…
using Symbolics
julia> @variables a x y x̄ ȳ
5-element Vector{Num}:
a
x
y
x̄
ȳ
julia> simplify(a*y + a*ȳ)
a*(y + ȳ)
% julia
…
julia> using Symbolics
julia> @variables b x y x̄ ȳ
5-element Vector{Num}:
b
x
y
x̄
ȳ
julia> simplify(b*y + b*ȳ)
b*y + b*ȳ
% julia
…
julia> using Symbolics
julia> @variables c x y x̄ ȳ
5-element Vector{Num}:
c
x
y
x̄
ȳ
julia> simplify(c*y + c*ȳ)
c*(y + ȳ)
% julia
…
julia> using Symbolics
julia> @variables d x y x̄ ȳ
5-element Vector{Num}:
d
x
y
x̄
ȳ
julia> simplify(d*y + d*ȳ)
d*y + d*ȳ
% julia
…
julia> using Symbolics
julia> @variables e x y x̄ ȳ
5-element Vector{Num}:
e
x
y
x̄
ȳ
julia> simplify(e*y + e*ȳ)
e*y + e*ȳ
```