When we have an item with the marker immediately to the left of some
non-terminal, then this tells us that the next step in the parse is to
recognise some sequence of symbols which correspond to this
non-terminal. To do this, we have to examine the rules for that
non-terminal, and proceed from there.
For instance, the item
tells us that the next step is to recognise a ; we can do this by
recognising one of the two r.h.s. of the production rules for .
This item is thus equivalent to:
and
.
An item with the `` '' on the far left of the r.h.s. is called a non-kernel item. Anywhere we have the `` '' to the immediate left of a non-terminal is equivalent to each of the non-kernel items for that non-terminal.