case a new sensor is z2 and when we see z2 it actually is more likely to be seen when the door is not open we observe z2 so what do you expect to happen mathematically we had a 2/3 probability of the door being open ahead of time after sensor measurement 1 we observe z2 that probability should drop but let's check we can do the math we just apply Bayes rule fill in the numbers and indeed the probability drops as we expected all right now there is one thing I want to point out here is that a typical pitfall is that real-world