The Paper regarding die SHAP value gives a formula for the Shapley Values in (4) and for SHAP values apparently (?) in (8)
Still I dont really understand the difference between Shapley and SHAP values. As far as i understand for Shapley I need to retrain my Model on each possible subset of parameters and for SHAP i am just using the basic model trained on all parameters. Is that it? So SHAP is computationally easier?