9.9 Exercises Exercise 9.1 (Printer Nightmare). Cheapco is, quite honestly, a pain in the neck. Not only did they buy a dodgy old laser printer from StopPress and use it mercilessly, but try to get...

Exercises Fuse Drum Toner Paper Roller Burning Quality Wrinkled Mult. Pages Paper Jam Figure9.21: PrinterNightmarebeliefnetwork. Allvariablesarebinary. Theuppervariableswithoutparents are possible problems (diagnoses), and the lower variables consequences of problems (faults). 9.9 Exercises Exercise 9.1 (Printer Nightmare). Cheapco is, quite honestly, a pain in the neck. Not only did they buy a dodgy old laser printer from StopPress and use it mercilessly, but try to get away with using substandard components and materials. Unfortunately for StopPress, they have a contract to maintain Cheapco’s old warhorse, and end up frequently sending the mechanic out to repair the printer. They decide to make a statistical model of Cheapco’s printer, so that they will have a reasonable idea of the fault based only on the information that Cheapco’s secretary tells them on the phone. In that way, StopPress hopes to be able to send out to Cheapco only a junior repair mechanic, having most likely diagnosed the fault over the phone. Based on the manufacturer’s information, StopPress has a good idea of the dependencies in the printer, and what is likely to directly a? ect other printer components. The belief network in ?g(9.21) represents these assumptions. However, the speci?c way that Cheapco abuse their printer is a mystery, so that the exact probabilistic relationships between the faults and problems is idiosyncratic to Cheapco. StopPress has the following table of faults in which each column represents a visit. fuse assembly malfunction 0 0 0 1 0 0 0 0 0 0 0 0 1 0 1 drum unit 0 0 0 0 1 0 0 1 0 0 1 1 0 0 0 toner out 1 1 0 0 0 1 0 1 0 0 0 1 0 0 0 poor paper quality 1 0 1 0 1 0 1 0 1 1 0 1 1 0 0 worn roller 0 0 0 0 0 0 1 0 0 0 0 0 0 1 1 burning smell 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 poor print quality 1 1 1 0 1 1 0 1 0 0 1 1 0 0 0 wrinkled pages 0 0 1 0 0 0 0 0 1 0 0 0 1 1 1 multiple pages fed 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 paper jam 0 0 1 1 0 0 1 1 1 1 0 0 0 1 0 1. The above table...