program it's going to solve a problem you have some finite description of some program and this program can take an arbitrarily long inputs and still solve the problem okay if you give it an input of length 10 no problem input of length of thousand no problem a million no problem 100 million no problem this thing always solves the problem single thing okay that is in contrast with the circuit model where we only allow you to take in fixed length inputs okay so so if we're thinking about how our circuits can relate to one another we've