Not sure if this is the intended behavior:
using Symbolics @variables x simplify(sin(x) + sin(-x))
sin(x) + sin(-x)
instead of 0, which is really surprising. Then checked if I could write down a rewriting rule using SymbolicUtils.jl like this:
using SymbolicUtils @syms a r = @rule sin(-(~a)) => -sin(~a) r(sin(-a))
which prints nothing! Am I doing something wrong here?