§3.3. One-way connections

Connections are ordinarily two-way, but do not have to be. One of the map connections in the Mammoth Cave simulation was made by the sentence:

The Debris Room is west of the Crawl.

Besides reading this sentence at face value, Inform also deduced that the Crawl was probably meant to be east of the Debris Room: in other words, that the path between them is a two-way one. When Inform makes guesses like this, it treats them as being less certain than anything explicitly stated in the source. Inform will quietly overturn its assumption if information comes to hand which shows that it was wrong. That might happen in this case if another sentence read:

The Hidden Alcove is east of the Debris Room.

These two sentences are not contradictory: Inform allows them both, simply accepting that the world is more complicated than it first assumed. There are relatively few situations where Inform has to make educated guesses, but when it does, it tries always to follow Occam's Razor by constructing the simplest model world consistent with the information in the Source text.

We can even explicitly make a route which turns around as it leads between two rooms:

West of the Garden is south of the Meadow.

If we want to establish a route which cannot be retraced at all, we can specify that a particular direction leads nowhere:

East of the Debris Room is nowhere.

Finally, note that Inform's assumptions about two-way directions are only applied to simple sentences. When the source text seems to be saying something complicated, Inform takes it as a precise description of what's wanted. So, for example, in:

The Attic is above the Parlour.
The Attic is a dark room above the Parlour.

Inform makes guesses about the first sentence, and makes a two-way connection; but it accepts the second sentence more precisely, with just a one-way connection.

 Start of Chapter 3: Things Back to §3.2. Rooms and the map Onward to §3.4. Regions and the index map

 ExamplePort Royal 2 Another part of Port Royal, with less typical map connections.

 ExampleThe Unbuttoned Elevator Affair A simple elevator connecting two floors which is operated simply by walking in and out, and has no buttons or fancy doors.