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## Tossing a Coin

In Section 4.2.3 we described a plan for ending up with a flat coin. The decision in this plan does not distinguish between the coin landing heads-up and tails-up---the decision rules are ambiguous.

```Initial:       (HOLDING-COIN)

Step  1 (2): (TOSS-COIN)
(AND (NOT (HOLDING-COIN)) (ON-TABLE))
0 -> (HOLDING-COIN)

Step  2 (4): (INSPECT-COIN)
(AND (KNOW-IF (FLAT-COIN)) (KNOW-IF (HEADS-UP))
(KNOW-IF (TAILS-UP)) (KNOW-IF (ON-EDGE)))

Step  3 (3): (DECIDE UNK2S)
(and (FLAT-COIN)
T                ) => [UNK2S: H]
(and (FLAT-COIN)
T                ) => [UNK2S: T]
(and (ON-EDGE)
T                ) => [UNK2S: E]
2 -> (KNOW-IF (FLAT-COIN))
2 -> (KNOW-IF (ON-EDGE))

Step  4 (1): (TIP-COIN)                           YES: [UNK2S: E]
NO : [UNK2S: H T]
(FLAT-COIN)
1 -> (ON-EDGE)                  NO : [UNK2S: H T]

Goal:        (FLAT-COIN)

GOAL                                 YES: [UNK2S: T]
1 -> (FLAT-COIN)                NO : [UNK2S: H E]

GOAL                                 YES: [UNK2S: H]
1 -> (FLAT-COIN)                NO : [UNK2S: T E]

GOAL                                 YES: [UNK2S: E]
4 -> (FLAT-COIN)                NO : [UNK2S: H T]

Complete!
```

Next: Tossing Another Coin Up: Cassandra's Plans Previous: Fetching Another Package

Louise Pryor <louisep@aisb.ed.ac.uk>;
Last modified: Mon Mar 18 18:33:22 1996