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This folder contains a Logtalk version of a spreading activation nodes
backtracking example described in the Net-Clause Language (NCL) manual,
available at:

https://www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/prolog/impl/parallel/ncl/0.html

The Logtalk version uses parametric objects to represent the concept of
"net-variables" described in the paper as "global logical variables" and
events to implement the functionality of spreading activation nodes.
When multiple spreading activation nodes fire, all their procedures must
be true by default (in the NCL manual, this corresponds to `netmode(3)`).

Print Logtalk, Prolog backend, and kernel versions (if running as a notebook):

```logtalk
%versions
```

Load the example:

```logtalk
logtalk_load(backtracking_nodes(loader)).
```

Run the example:

```logtalk
backtracking(X,Y,Z)::(n(2), n(1), n(3)), bagof(E, backtracking(X,Y,Z)::n(E), L).
```

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