Ultimate Engineering Study Guide - Questions & Answers
Using the deterministic Model and given the following page reference string: 1,2,5,7,2,6,5,4,2,1,8,7,8,7,8,5,2,9,5,2,1,2,3,2,7,9. How many page faults would occur for each of the following 2 replacement algorithms assuming 4 frames? [Optimal, LRU] Use pure-demand paging. Show your work. LRU: OPT:
PART I We want to build a data warehouse to store information on country consultations. In particular, we want to know the number of consultations, in relation to different criteria (people, doctors, specialties, etc. This information is stored in the following relationships: PERSON (Person_id, name, phone, address, gender) DOCTOR (Dr_id, tel, address, specialty)CONSULTATION (Dr_id, Person_id, date, price) Tasks :1. What is the fact table? 2. What are the facts? 3. How many dimensions have been selected? What are they? 4. What are the dimension hierarchies? Draw them. 5. Propose a relational diagram that takes into account the date, the day of the week, month, quarter and year.
What is the point of the EM algorithm? Select the best option below. Be careful to consider the distinction between calculation of a probability (given some implicit parametric form) and maximization of a probability (by choosing the parameters directly.)A. The purpose of EM is to maximize the observed data likelihood P(X) when the joint likelihood P(X,Z) is tractable, but the hidden variables Z are not known. It does reduce the complexity of calculating P(X), so it works best when both P(X) and P(X,Z) can be evaluated in polynomial time.B. The purpose of EM is to maximize the observed data likelihood P(X) when the joint likelihood P(X,Z) is tractable, but the hidden variables Z are not known. It also allows us to tractably approximate the P(X) even when exact computation is exponential.C. The main application of EM is to obtain samples from the joint distribution P(X,Z) which can then be used as training data.D. EM can be used to handle exponential sums arising from inference problems. I.e., the EM algorithm canbe used to calculate P(X) in polynomial time even when there are many nusiance variables that have to be summed out from the joint distribution, P(X,Z).