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Outline

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Electrical Engineering UET Lahore (2001-2005) ... Find 3 hotels closest to Islamabad Airport. A Brute Force Solution. Algorithm: ... – PowerPoint PPT presentation

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Title: Outline


1
Outline
  • Who am I?
  • What is research?
  • My Research
  • Higher studies opportunities in Australia
  • Getting jobs in IT industry
  • Presented by
  • Muhammad Aamir Cheema, Lecturer IT at James Cook
    University Australia, Sydney campus

2
Who Am I? A Student
  • BSc. Electrical Engineering UET Lahore
    (2001-2005)
  • Masters by research University of New South Wales
    (UNSW) Sydney (2005-2007)
  • Currently a PhD Student at UNSW Sydney
  • Research Area Databases

3
Who Am I? A Teacher
  • Tutor _at_ University of New South Wales, Sydney
  • Lecturer IT _at_ James Cook University Sydney Campus
  • Courses Taught
  • Database Systems Implementation
  • Database Systems
  • Operating Systems and Architectures
  • E-Business Technologies
  • Portable Programming
  • C

4
What is Research?
  • Formally a form of systematic enquiry that
    contributes to knowledge.
  • Is research boring and difficult???
  • NOT AT ALL if you like solving puzzles
  • Informally,
  • Research Solving Puzzles

5
Lets Play a Game1
  • Task Find the missing number
  • Given Data set consists of numbers from 1 to
    20
  • Version 1
  • Numbers are not displayed on the screen
  • Version 2
  • Find the missing number from the list below
  • 4,2,8,18,1,20,17,9,16,15,13,3
    ,12,19,6,5,14,7,10
  • Version 1 is more difficult because
  • No element can be seen twice
  • We cannot memorize all the numbers

1- Data Streams Algorithms and Applications, S.
Muthukrishnan
6
Brute Force Solution for Version 2
  • 4,2,8,1,10,9,5,3,6
  • Is 1 missing?
  • Is 2 missing?
  • Is 3 missing? . . .
  • Algorithm
  • For each number i from 1 to n
  • Check whether i is missing or not
  • Performance
  • Space Usage (n-1) elements ? O(n)
  • Running Time O(n2)

7
Sorting A faster solution
  • 4,2,8,1,10,9,5,3,6
  • 1,2,3,4,5,6,8,9,10
  • Sort the numbers
  • Scan the list to find missing number
  • Performance
  • Space Storage O(n)
  • Running Time sorting time final scan
  • nlogn n ? O(nlogn)

8
Bucket Even faster approach
  • 4,2,8,1,10,9,5,3,6
  • Algorithm
  • create an empty array of size n
  • For each element i in the list
  • Mark the element at index i
  • Unmarked index is the missing number
  • Performance
  • Space Requirement O(n)
  • Running Time O(n)

9
Solution for Version 1???
  • What we have done so far
  • Developed solution for Version 2
  • Performance Space Usage O(n)
  • Running Time O(n)
  • Version 1
  • A solution is required that
  • Accesses each element only once Running Time
    O(n)
  • Memorizes only one number Space Usage
    O(1)
  • An example application data passing through a
    network node (e.g a router cannot store all the
    data passing through it and can see each element
    only once)

10
Hint
  • Given numbers are from 1 to 10
  • Task Nine numbers from the data are sent to user
    one by one, find the missing number
  • Sum of the numbers from 1 to 10 is 55

11
Solution
  • Given Numbers are from 1 to n
  • Algorithm
  • Find the sum of 1 to n numbers? Sn(n1)/2
  • For each number i
  • SS-i
  • S is missing number
  • Performance
  • Space Usage O(1)
  • Running Time O(n)

12
My Research
  • Nearest Neighbors Problem
  • Given a set of objects O, find k objects closest
    to any given query object
  • Objects are represented by their location
    coordinates
  • Applications
  • Find 5 taxis nearest to my current location
  • Find 3 hotels closest to Islamabad Airport

13
A Brute Force Solution
  • Algorithm
  • Let q be the query object
  • For each object x
  • Find the distance of x from q
  • Report the k objects with the minimum distance
    from q

14
Problems with the brute force approach
  • Distance of all objects from the query object is
    to be calculated Running Time O(n)
  • What if all the objects are moving (e.g cars on a
    road)???
  • To update the results, compute distance of all
    objects again

15
A better solution
  • Compute the distance of only the objects in
    vicinity of the query object q
  • How to find the objects that lie in vicinity of
    q?
  • Use some spatial Index. i.e grid index

16
CircularTrip1
  • Explore the objects around q in an iteratively
    increased circle
  • Use grid based index (visit the cells around q
    that intersect the circle)

p1
q
r
p2
  • 1- Muhammad Aamir Cheema, Yidong Yuan, Xuemin
    Lin, "CircularTrip An Effective Algorithm for
    Continuous kNN Queries", DASFAA 2007, Thailand.

17
Updating the result on movement of objects
  • Incoming objects any non-result object p
    entering inside the circle
  • Insert p into answer list
  • Outgoing objects any result object leaving the
    circle
  • delete p from answer list
  • Hanlde all the object updates as mentioned above
  • Case 1 answer list contains k or more than k
    objects
  • Keep k closest objects and discard other
  • Case 2 answer list contains less than k objects
  • Same as initial computation except the starting
    radius is distk

p1
q
distk
p2
18
Higher Studies Opportunities in Australia
  • Student Visa
  • Apply in any institution you like
  • Get admission letter
  • Take IELTS exam (you need 6 band overall)
  • Show bank statement
  • Permanent Visa
  • Get three year work experience in Pakistan
  • Take IELTS (minimum 7 band in each module)
  • Apply for Permanent residence (PR) visa
  • Go there and get education with benefits of being
    a citizen of Australia (e.g more scholarship
    opportunities, HEC loan etc)

19
Higher studies opportunities in Australia
  • Student Visa
  • Quick (you will not need to wait to complete 3
    yrs work experience to get PR)
  • You become eligible for PR once you complete your
    degree (duration must be at least 2 years) in
    Australia
  • Permanent Visa
  • Less expensive (once you are citizen your
    chances of getting scholarship grow enormously)

20
When Australia?
  • Education in Australia is not cheap but Australia
    is accomodating
  • Prefer European countries or try HEC scholarships
    if you are not interested in settling abroad

21
Getting Jobs in IT industry
  • University degrees teach you little bit of
    everything
  • A regular student becomes Jack of all trades but
    master of none
  • To get good jobs, you must become Jack of all
    trades AND master of ONE
  • Moral Be master in at least on skill. e.g JAVA,
    C, networking, web development etc.

Try to learn something about everything and
everything about something
22
Contact Information
  • www.cse.unsw.edu.au/macheema
  • Google search Muhammad Aamir Cheema
  • macheema_at_cse.unsw.edu.au
  • THANKS
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