Stuttering in search trees arises when moves in the search tree can go back and forth between the same states. For example, in the Towers of Hanoi one could repeatedly move a ring form tower 1 to 2 on the forts movem then form 2 to one on the next move and so on. A closed list can be used to record visited states and hence avoid stuttering.
Defined on page 66
Used on Chap. 4: pages 62, 66