A possible way out is to restrict the analysis on a finite-dimensional subspace as an approximation of the full theory space. In other words, such a truncation of the theory space sets all but a finite number of couplings to zero, considering only the reduced basis { P α α [ ⋅ ⋅ ] } with α α = 1 , ⋯ ⋯ , N . This amounts to the ansatz