# `Mnemosyne.ValueFunction`
[🔗](https://github.com/edlontech/mnemosyne/blob/main/lib/mnemosyne/value_function.ex#L1)

Behaviour for scoring memory nodes during retrieval.

Implementations combine raw cosine relevance with node metadata
(recency, frequency, reward) to produce a final score.

# `score`

```elixir
@callback score(
  relevance :: float(),
  node :: struct(),
  metadata :: map() | nil,
  params :: map()
) :: float()
```

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*Consult [api-reference.md](api-reference.md) for complete listing*