--- In

aima-talk@yahoogroups.com, "kiana" <blacksilk79@...> wrote:

>

> I understand the material in the chapter. However, the exercises

are

> completely confusing to me. Therefore, a discussion of the chapter

may

> clarify. For the 8-puzzle problem, I am not able to understand the

> existence of two disjoint sets of all possible states in which a

state

> from one set can't transform to a state in the other set by any

number

> of moves. I would assume any state can be reached by in other

state. In

> other words, there are situations (initial state - goal

configuration)

> in which the puzzle isn't solvable? Does the two disjoint sets exit

> because the problem becomes an NP-Complete problem for those states

> trying to reach the states in the other disjoint set. And, the 9!/2

> calculation for all possible states derives from this theorem of

> exactly half of the possible states transform into a given goal, is

> this true?

>

Discussions of the topics in the book leads to a better understanding

of the material. I need clarification of the topics in order to

answer the exercies, not necessarily the answer to the questions. In

order for me to understand the material further, I need to understand

the questions. The existence of the disjoint sets were discussed in

book, so I would like to elaborate on that topic. I don't understand

that section of the book. Thank you.