If c0  |–n cn [r] for some n ³ 1, then
 c0  |–+ cn [r].
If c0  |–n cn [r] for some n ³ 0, then
 c0  |–* cn [r].
Example: Consider
pabc |– qbc [1: pa ® q], and qbc |– rc [2: qb ® r].
Then, pabc |–2 rc [1 2], pabc |–+ rc [1 2], pabc |–* rc [1 2]
Sequence of Moves 2/2
15/29