well, there's some really basic semantics, that can be summed up in the most fundamental equation of arithmetic and the root of algebra:

1 + 1 = 2

change it to symbols:

a * 2 = b

b = a  / 2

and because of these, this also holds:

a != b

you literally can't write software if you are wishy washy about whether a = b in this case, because the program above it implies it absolutely is not

one is related to the other

not equal to the other

you can't be related and equal at the same time, or you deny the very principle of identity, which is central to arithmetic and algebra

if a can be anything, why waste time trying to figure out what it is

no, we have another concept for that, it's called a "wildcard" and is generally represented in algebra as X