CS5430 Homework 1: Adversarial Thinking

General Instructions. You are expected to work alone on this assignment.

Due: Jan 29 (Wed) 11:59pm. No late assignments will be accepted.

Submit your solution using CMS. Prepare your solution as .pdf, as follows:


Recall, attendance at cs5430 lectures is required. Various schemes might be employed to determine that a student has attended all of the lectures. The requirements for such a scheme are: So the utility of a proposed scheme might be evaluated in terms of: (i) whether it has vulnerabilities that allow a student to miss lecture without being caught, (ii) the costs, and (iii) other issues.

Problem 1. Analyze each of the following proposed schemes, giving your assessment in terms of (i) through (iii). Assume that the scheme is implemented exactly as described. As an example of the kind of answer we are expecting, we give such an analysis for a scheme used in many classes where attendance matters.

Scheme 0: Roll Call. At the start of class, the professor calls each student's name from a registration list. When a student's name is called, that student -- if present -- is expected to reply "present". The professor records those answers (or lack thereof) on the list, which is kept in the professor's office.

ANSWER: (i) Vulnerabilities: One student might answer for another, so a student's absence can be hidden if a friend is willing to help. (ii) Costs: Time is lost at the start of lecture. If 10 names can be called per minute, then a class with 100 students would have 10 minutes lost at the start of each lecture. (iii) Other issues: The scheme does not gracefully handle students who arrive at lecture late.

Scheme 1: Random Polling. A separate piece of paper with each student's name is printed and placed in a hat. Before the end of each class, the professor randomly selects 10 of these chits from the hat; the name on each of those chits is read aloud. If a student whose name is read is present, then that student is expected to reply "present". The professor records the date and absence of an answer on a list. The chits that were removed are returned to the hat for possible selection next time.

Scheme 2: Swipe Card at Entry. An ID card reader is located at each entrance to the lecture room. When a student arrives for class, that student swipes his/her ID card using the reader. Each time an ID card is swiped, the reader records in a file the name and number of the ID card. That file is downloaded by the professor at the end of the lecture.

Scheme 3: Clickers Each student is expected to have purchased a "clicker" and registered it, thereby establishing a binding between the "clicker" ID and the student's name. A student is expected to bring that "clicker" to class. During the course of the lecture, the professor asks at least one multiple-choice question. Students are expected to respond by using the "clicker".

Scheme 4: Random Pop Quiz At random points during the semester, the professor distributes a short quiz towards the end of the lecture. Students write answers on the quiz and, at the end of class that day, hand the single completed paper to a course staff member, who is standing at an exit.

Problem 2. (a) Suggest a better scheme. It should have fewer vulnerabilities, reasonable costs, and no significant other issues. (b) Analyze this proposed scheme, giving your assessment in terms of (i) through (iii).