what is the objective function in pFBA using forward+backward fluxes?

[shaicoh3n]

I know that the objective function is to minimize the sum of the absolute of the fluxes. I'm wondering if that means using the forward (v_f) and backward (v_b) fluxes it will be sum over |v_f-v_b| or |v_f+v_b| or something else?

[cdiener]

It's the sum over v_f+v_b. That works for minimization (only) because there min | v_f - v_b | = k always implies a solution where either v_f or v_b must be zero and the other one will be +-k.

[shaicoh3n]

thx, It is v_b+v_f :)

[shaicoh3n]

It is v_b+v_f :)