Hi @AlejandroCatalina, I have a brms model (Bernoulli family), which is a simpler version of what I was describing in Advice on using search_terms in projpred. The formula is:

```
Y ~ (X1 + X2 + X3 + X4 ) * F1 * F2
```

`X1`

to `X4`

are four different continuous predictors, `F1`

and `F2`

are factors with 2 and 5 levels respectively.

I want to use projpred to help determine which of the X should be included in the model because they improve predictions in any of the 2 x 5 = 10 conditions of the experiment. This means that whenever any `X`

is included, I also want to include all of its interactions with `F1`

and `F2`

. In an attempt to do this in propred, I have specified :

```
search_terms = c(
"1",
"F1 + F2 + F1:F2 + X1 + X1:F1 + X1:F2 + X1:F1:F2",
"F1 + F2 + F1:F2 + X2 + X2:F1 + X2:F2 + X2:F1:F2",
"F1 + F2 + F1:F2 + X3 + X3:F1 + X3:F2 + X3:F1:F2",
"F1 + F2 + F1:F2 + X4 + X4:F1 + X4:F2 + X4:F1:F2")
```

However, when I run `vs <- varsel(mdl, search_terms = search_terms)`

, `vs$solution_terms`

shows 19 entries each of which is a single item (e.g., `F1`

, `F2`

, `X1:F1`

) and not the four different composite entries provided `search_terms.`

I have checked that the variable names in `search_terms`

match the names in the model formula, so I don’t understand what’s happening here. Have I made a mistake with the syntax, or maybe I am misunderstanding the output of `vs$solution_terms`

?