Compilation principle first collection follow set of the method

First set of methods:
The first collection is ultimately the string for the right side of the production, but the key is to find the first set of non-Terminator, since the first collection of Terminator is itself, so it is very straightforward to get the first collection of each string after finding the first set of non-terminator.
1. Direct charge: to form as u-a ... (where A is terminator) and the income from A to first (U)
2. Repeated transmission: to the shape into the u-p ... (where p is non-terminator), the entire contents of first (p) should be transmitted to first (U).
The method of follow collection:
The follow collection is for non-Terminator, and follow (U) is expressed as a set of all possible post-finalization symbols that are not terminator U, in particular, "#" is the post-attendant character of the recognition symbol.
1. Direct charge: Pay attention to the production of the right side of each shape, such as "... Ua ... "A direct income to follow (U).
2. To receive directly: to form as "... Up ... "(P is a non-terminator), and the first (p) proceeds directly into follow (U).
3. Repeated transmission: to form like u ... The production of P (where p is non-terminator), the entire contents of follow (U) should be transmitted to follow (P).