CS408 Assign 1 Solution Fall 2019

QUESTION 1: Solution
Consider the following scenario:

“Objects Identifier system (a mobile application) is designed to help the blind and visually impaired users to identify objects they encounter in their daily lives (e.g. Cup, Glass, plant or any object).”

You are required to:
a)      Choose a suitable combination of input and output devices to best support the intended interaction.
b)      What should be the features of the input and output devices that help the blind people to work on the given system?
c)      Explain the major problems that the input and output devices solve.
Note: You are supposed to describe at least one input and one output device for the intended

Solution Table:

Identify the goals, sub-goals and operators involved in given problem


“Open a File name (HCI-Notes) from D. drive and Update the second paragraph of page no. 20 in a file”.

Use a word processor to update a paragraph and note your actions, goals, sub-goals and operators.


Imagine you have a document open and you are at some capricious position within it. You furthermore necessaries to make a decision which operator are accessible and what their pre-conditions are:

Preconditions/ actions
Update paragraph
Cursor at edit of paragraph
Update paragraph
Move_to_ paragraph
Cursor anywhere in the document
Cursor moves in document to start of the next paragraph
Cursor anywhere in the document
Cursor at start of the document


Update second paragraph in document.

Looking at the operators an palpable one to make your mind up this aspiration is update paragraph which has the pre-condition ‘cursor at edit of paragraph’

We therefore have a new sub-goal: move to paragraph. The pre-condition is ‘cursor anywhere in document’ (which we can meet) cursor moves in document to start of the next paragraph .
We set up a new sub- goal, move to start, with pre-condition ‘cursor anywhere in document’ and result ‘cursor at start of document’. We can then apply move to paragraph and finally update paragraph.

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