Bottom up parsing

Today we will discuss bottom up parsing and parse tree
Bottom up Parsing:
Consider the following grammar G1 again:
E ::= E + T | E - T | T
T ::= T * F | T / F | F
F ::= num | id
In contrast to top-down parsing, bottom-up parsing starts from the input string and uses derivations in the opposite directions (ie, by replacing the RHS sequence X1X2...Xn of a production A : : = X1X2...Xn with the non-terminal A. It stops when it derives the start symbol. For example,
id(x) + num(2) * id(y)
=> id(x) + num(2) * F
=> id(x) + F * F
=> id(x) + T * F
=> id(x) + T
=> F + T
=> T + T
=> E + T
=> E