[Feature]: More constant symplification?

[Moelf]

Feature Request

atlas_template = TemplateStructure{(:b, :e)}(
     ((; b, e), (x,)) -> b(x)^e(log(x))
)

sr_model2 = SRRegressor(
    niterations=150,
    binary_operators=[+, -, *, ^],
    unary_operators=[log],
    should_optimize_constants=true,
    seed=nothing,
    nested_constraints = [log => [log => 0, (^) => 0]],
    expression_type=TemplateExpression,
    expression_options=(; structure=atlas_template),
    loss_function = chi2_sr
)

sr_mach2 = machine(sr_model2, X, ys)

fit!(sr_mach2)

log(162.43) shouldn't use log at all (this increase the complexity of the expression unnecessarily)

[MilesCranmer]

You likely just need to set should_simplify=true. By default this is set to false if you are using nested_constraints as simplification might result in an expression that violates constraints. I think here though it's fine.

[MilesCranmer]

But in general there will be some points when the expression has redundancies like this. The genetic algorithm should eventually simplify it based on a lower complexity.

[MilesCranmer]

Also - we don't want to necessarily force simplified expressions. This is because mutations are single-step, so to get to log(x + const), the genetic algorithm might prefer to go from const to log(const) to log(x + const), rather than x to log(x) to log(x + const) which might hit a NaN. If we force simplification at every step, the log(const) expression wouldn't be possible.

[Moelf]

It is already set to true

[MilesCranmer]

Oh in the code you sent, it isn't set at all:

julia> print(sr_model2.should_simplify)
nothing

It will be set to false during the search based on the other parameters set.

Maybe you meant should_simplify instead of should_optimize_constants?

[MilesCranmer]

(Is this ok to close? Or any issues with it?)