Presumably the poster would have about as much as a problem if the author picked the first 14 letters of the English alphabet.also, it is not a given that everyone knows the green alphabet, and it is harder to correlate symbols when you don't have familiarity and know the names of them.
Just for the record, those aren't the first letters the Greek alphabet, nor are they in order, given that alpha is shortly after omega and both are near the center of the list.
I assume they follow some standard of usage in context, but I don't know enough about economics to know what they're normally used to represent.
If you're going to be the kind of person who reads technical papers, you should also be the kind of person who knows the Greek alphabet, it's only got 24 letters and not all of them are generally used.
