## PLN Semantics

In

```AttractionLink <TV>
X
Y
```

the TV on the AttractionLink represents the difference between ${\displaystyle P(Y|X)}$ and ${\displaystyle P(Y|\neg X)}$, we say that X is attracted to Y. For instance if X and Y are concepts, the strength of TV (letting aside the influence of confidence for now) will be

${\displaystyle TV.s=(TV1.s-TV2.s)^{+}}$

where TV1.s and TV2.s are defined with

```SubsetLink <TV1>
X
Y
```
```SubsetLink <TV2>
Not X
Y
```

and ${\displaystyle x^{+}}$ is the positive part of ${\displaystyle x}$. Note that the resulting TV of the attraction link is not a probability (or at least not obviously so).

## Related

See PredicateFormulaLink for an example of specifying formulas in Atomese.