Difference between Left Factoring and Left Recursion

Question

What is the difference between Left Factoring and Left Recursion ? I understand that Left factoring is a predictive top down parsing t

Answer 1

Here is a simple way to differentiate between both terms:

• Left Recursion: When leftmost Element of a production is the Producing element itself (Non Terminal Element).

e.g. A -> Aα / Aβ

• Left Factoring: When leftmost Element of a production (Terminal element) is repeated in the same production.

e.g. A -> αB / αC

Furthermore, If a Grammar is Left Recursive, it might result into infinite loop hence we need to Eliminate Left Recursion.

If a Grammar is Left Factoring, it confuses the parser hence we need to Remove Left Factoring as well.