 The core of an LR(1) item [S → a A • B e, c] is the LR(0) item S → a A • B e. Different LR(1) items may share the same core.For example, in item set 2

the parser is required to perform the reduction [E → T] if the next symbol is '$', but to do a shift if the next symbol is '+'.Note that a LR(0) parser would not be able to make this decision, as it only considers the core of the items, and would thus report a shift/reduce conflict.