pre or probability which is two - two - and why - ders - length you know I could explain length of this program so longer programs are punished yeah a priori and then you multiplied with the so called likelihood function yeah which is as the name suggests is how likely is this model given the data at hand so if you have a very wrong model it's very unlikely that this model is true so it this very small number so even if the model is simple it gets penalized by that and what you do is then you take just the sum word this is the average