...walking.

Thus we protect our flank from the disciples of Rod Brooks.

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...rich

Though rich, situations are still approximate, partial objects. The idea will be developed elsewhere.

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...ordered

Hypothetical situations need not be totally ordered; the situation where Oswald missed Kennedy is neither in the past nor the future.

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...forbade

Reiter [Rei93] did write such axioms.

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...preference.

Nevertheless, some narratives are anomalous. If we record that Junior flew to Moscow, and, in the next situation mentioned, assert that he is in Peking, a reader will feel that something has been left out.

We want to introduce a concept of a proper narrative, this is a narrative without anomalies. The fluents holding in a new situation should be reasonable outcomes of the events that have been reported, except for those fluents which are newly asserted, e.g. that it was raining in London when Franklin arrived.

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...actions

More precisely, no other actions that would move the blocks mentioned in the narrative occur. Other blocks might be stacked in Baghdad, if our narrative is about New York. Perhaps a theory of context, that would interpret a statement about all blocks in our narrative, as a statement about all the blocks in New York could be used here.

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...occur

Pinto and Reiter [PR95] actually do this.

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...situation

We could choose instead to make 5#5 a partial function, but this introduces the difficulties of partial functions.

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...axioms

Reiter's notation differ from ours, he uses do(a,s), while we use 6#6. We use 7#7 as a shorthand for 8#8. Reiter writes < as 9#9.

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...like

As is customary in Logical A.I. we write 15#15 without saying who is dead. We can suppose the events occur in a context and lifting rules exist to make this Dead(Victim) in an outer context. The outer context may contain further preconditions, like that shooter is present.

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...write

We will slightly abuse notation and write 20#20 for 21#21, when g is a predicate on fluents.

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...entire

The entire duration is taken to be up to, but not including the endpoint. It is sometimes natural that the endpoint should not be needed as a precondition.

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...Glasgow

We write the general formula with a variable l for Glasgow.

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...sets

Here we assume that we have a fluent function 29#29, such that 30#30 In the absence of the fluent function 29#29, we would need four sets, two for positive fluents and two for negative fluents.

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...interval

We need to state that no event whose result lies in the interval or at the endpoints, thus the use of 44#44. Sometimes, especially when we are checking preconditions of events, we will only need to show that nothing had an effect strictly before the end, and this we will only need to show <. When we try to use inertia we will need to show the 44#44.

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...sufficed

In this paper we state that the other events do not happen monotonically. These statements can be inferred non-monotonically from sentences that tell which occurrences and what fluents are explicitly stated to occur and hold in our narrative, and the axiomatization of Changes. A fluent is relevant if it is a precondition or an effect of a stated event that occurs, or if the fluent's value is stated in the narrative. This gives us a notion of what the relevant fluents and events are in terms of what fluents and events are explicitly given in the narrative. We then state that no other events occur that would change the effects of the relevant fluents. We avoid explaining this reasoning, as the machinery we currently use is quite complex.

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...air-hostess

If we wished that the air-hostess took Junior's ticket at another time, we might use our three argument version of result and write,

 55#55

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...fact

Whether or not the stronger fact is warranted depends on whether we wish to state that no event that might cause Junior to lose his ticket happens, or no event that does cause Junior to lose his ticket happens.

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...stacking

If we wish to restrict this to block stacking in New York we would add a conjunct 62#62 to the left hand side of the implication.

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...locations

These are not the same as geographical locations like New York or London. We use l to range over both, which is unfortunate.

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