Sunday, February 7, 2010

Human Centered Computing Exam: HCI

HCI Question 1 – 100 points:
The interface for a typical elevator is still based on physical buttons that allow the user to select a specific floor, hold the door open, close the door, or ring the alarm bell. With the price of flat panel displays dropping, it is possible that in the coming years we will see touch screen LCD panels replacing the existing designs.
A – What are the advantages of completely replacing a typical elevator button panel like the one
shown below with a touch-screen LCD panel?

Completely replacing the panel would allow for more information to be presented. There would be fewer individual mechanical pieces that could go faulty. Particularly in the case of some mechanical error, the LCD screen could provide information about what had happened to the caller to be relayed to the technician.

B – What are the disadvantages of that complete replacement?

With all changes there is a learning curve, and the newness may cause some confusion. Going beyond that, an LCD screen is unlikely to provide the same immediate feedback when a 'button' is pushed.

C – Suggest a hybrid design combining the current interface and an LCD touch screen that
maximizes the advantages and minimizes the disadvantages. Note which principles you
are using and how they affect your design.

HCI Question 2 – 33 points:
On some computer systems, using a mouse to move the cursor to the corner of the screen causes the system to sleep or go into alternative display modes. Is this a Fitts’ task? Explain your answer.

Yes, this task is a Fitts task. Since Fitts' Law deals with the placement and utilization of space for the distribution of objects for a task, placing the most frequently used objects near the center of the task, the act of placing a common task that shouldn't interfere with normal use at the edges of the screen falls under that umbrella of tasks.

HCI Question 3 – 34 points:
Touch-screen interactions often face the problem that the user’s finger occludes the object being
manipulated (e.g., selected, moved).
A - Describe two techniques that might potentially mitigate this problem, and discuss the
advantages and disadvantages of each technique.

One technique would be to have an offset of the touch, displaying the selection as slightly above(to avoid occlusion by the rest of the finger) of the contact. The advantage of this technique

B - Describe a procedure (including subjects, tasks, and analysis methods) for characterizing the
performance of the two proposed methods.

More later. Need to go back to foundations and really hard core study so...backing away from this for now. I feel this is easier and more comfortable than hard comp sci, and that's not cool.

Tuesday, February 2, 2010

Qualifier Practice Exam : Foundations

Part III: Theory of Computation (40 pts)
Question 1 (3 Points): Consider the following language over the alphabet of the 10
decimal digits (i.e., {0, 1, , 2, 3, 4, 5, 6, 7, 8, 9}):
L = {n : n = closing price of oil rounded to nearest U.S. dollar on Dec. 29, 2017}
What is the smallest class of languages of which L is a member?

(a) Languages decidable in linear deterministic time.
(b) NP
(c) NP-complete languages (?)
(d) P
(e) The undecidable languages

Question 2 (3 Points): The FUBAR problem is a new decision problem that you have
just begun to study. So far you have been able to show the following two things about the
FUBAR problem:
• There is a polynomial-time reduction from the Satisfiability problem (“Is a given
Boolean formula satisfiable?”) to the FUBAR problem.
• You have a nondeterministic method that solves the FUBAR problem and that never
consumes more than a polynomial amount of space.
What do you know for sure about the FUBAR problem given current knowledge?
(a) It is NP complete
(b) It is in the complexity class NP
(c) It is in the complexity class P
(d) It is not in the complexity class P
(e) It is NP hard.

Question 3 (4 Points): The minimum number of states of a Deterministic Finite State
Automaton (DFSA) over the alphabet {0, 1} recognizing the language containing the single
string of n 0s (n is fixed) is:
(a) 2n (b) n + 2 (c) n^2 (d) 10. (no)
Not sure if this is saying 0*1*(0^n)1*0* or just 0^n

Question 4 (4 Points): Let L be the language over {0, 1} consisting of all strings that
have a 1 in the third symbol from the end (e.g., the string 0100 is in L). The minimum
number of states of a DFSA recognizing L is:
(a) 50 (b) 5 (c) 8 (d) 100.