is and then the cross-entropy loss takes all of this and does the following there's a sum over all your classes in this case you have three classes and let's call these the labels l and you want to always take the label of the class times the log probability that the network thinks belongs to this class so you can quickly see that this if the label is 0 so for all the incorrect classes that means this entire term drops away and only if the label is 1 so only the correct class that will result in the log probability of the class