Algo.2013f-exam History

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# Q1: my construction of gadget II is wrong (why?). Can you find the correct construction?
to:
# Q1: my construction of gadget II is wrong (why?). Can you find the correct construction? \\
[SOLUTION: use 2 copies of gadget I as before. Their distinguished vertices are (A,B) and (A',B').\
Identify B with B'. Then introduce a new vertex C and form a triangle (A,A',C). Now A and C must have different color]
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# Q1: my construction of gadget II is wrong (why?). Can you find the correct construction?

# Q2: The problem should say "AT MOST B" not "AT LEAST B". Reason? We want to force the \
path to go through as many clauses as possible.
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COMMENTS ON SOLUTION:

# Q4: Claim C can be improved: v is a bottleneck iff it is a candidate. \
Thanks to Nguyen for pointing this out.

# Q5: The claim that we can find real bottlenecks in O(m+n) time is a bit subtle. \
We did not provide the details, but try to see if you can do this. Thanks to Nguyen for \
pointing this out.

# Q7: our solution actually uses this definition: An edge e=(i,j) is "essential" if C(e)=\delta(i,j). \
We do not actually ensure that there are no alternative paths from i to j with cost at most C(e). \
Doing this seems a bit tougher.
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Here is the [[(Attach:) StudyQuestions-sol.pdf]] (posted Dec 17).
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This will be on Thu, Dec 19, in usual classroom 312, from 3:30-7:30 pm. It is a closed-book exam.
to:
This will be on Thu, Dec 19, in usual classroom 312, from 3:30-7:30 pm.

It is a closed-book exam.
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We will collect them at the end of the exam.
to:
We will collect these sheets at the end of the exam.
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But we will allow a 8"x11" sheet (2-sided) of notes which you prepare in advance.
We will collect them at the end of the exam.
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!! Final Exam

This will be on Thu, Dec 19, in usual classroom 312, from 3:30-7:30 pm. It is a closed-book exam.

Here is a set of study questions [[(Attach:) StudyQuestions.pdf]]
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!! Final Exam

This will be on Dec 19, in usual classroom 312, from 3:30-7:30 pm.
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For AVL Trees, be familiar with the insert/delete as well as the Merge/Split \
algorithms (Split is described in solution of hw3) \\
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your rules for logarithms and exponentiations).
to:
your rules for logarithms and exponentiations). \
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Be sure you can do rotations and all the associated algorithms on actual trees.
to:
Be sure you can do rotations and all the associated algorithms on actual trees. \\
Since we disallow calculators, you are expected to do hand calculators (review \
your rules for logarithms and exponentiations).

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# Here are some technical remarks, based on your questions (click to expand):
to:
# Here are more remarks, based on your questions (click to expand):
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: Homework 3, question 10: This is a question about %green%min-size AVL trees%%. %toggle% :\
It is our
typo NOT to have said this. My intent is clear from the model answer. \
to:
: Homework 3, question 10 on height of AVL tree with 100 nodes: \
This is a question about %green%min-size AVL trees%%. %toggle% :\
It is a
typo NOT to have said this. My intent is clear from the model answer. \
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: In proofs, can I quote your theorems? %toggle% :\
YES, you can (probably SHOULD). Unless I specifically forbid it. \\
E.g., I might say, \
prove from first principles and do not quote the Master Theorem, etc. \\
Note that there is STILL some work to do, even if you quote theorems. \\
E.g., when quoting the Master Theorem, you still need to show that a particular \
case applies. That may require showing regularity, etc. \\
E.g., in estimating sums using our Rules for Polynomial-type or Exponential-type, \
you may need to justify why they are polynomial- or exponential-type.

: Hand Simulations %toggle% :\
Be sure you can do rotations and all the associated algorithms on actual trees.
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: Bug in Non-Recursive DFS %toggle% :\
Line 9-10 should be changed to: \\
%green% PREVISIT(v,u); If (v is unseen), then color v seen.%% \\
In short, you should ALWAYS do the PREVISIT. \\
This is clear, if you remember that PREVISIT amounts \
to processing the edge (u,v). Thanks to Huaisi for pointing this out.

: Homework 3, question 10: This is a question about %green%min-size AVL trees%%. %toggle% :\
It is our typo NOT to have said this. My intent is clear from the model answer. \
But you should answer the question without making this assumption! That is, you should \
always read a question literally. We will grade you accordingly.
October 06, 2013, at 08:01 PM EST by 128.122.253.212 -
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# Here are some technical remarks, based on your questions:
to:
# Here are some technical remarks, based on your questions (click to expand):
October 06, 2013, at 08:00 PM EST by 128.122.253.212 -
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Does "double rotation" just mean "rotate^2(u)"? %toggle% :\
to:
: Does "double rotation" just mean "rotate^2(u)"? %toggle% :\
October 06, 2013, at 07:58 PM EST by 128.122.253.212 -
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# This is an open-book exam, but not open-computer or electronic devices (or calculators).
to:
# This is an open-book exam, but not open-computer or electronic devices (or calculators). \
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# In terms of topics, you are technically responsible for everything up to
the lecture on Oct 8. That means the first 6 Lectures.
But the first 3 Lectures will be emphasized, especially on topics
to:
# In terms of topics, you are technically responsible for everything up to \
the
lecture on Oct 8. That means the first 6 Lectures. \
But
the first 3 Lectures will be emphasized, especially on topics \
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'''What is a 'double rotation'?''' %toggle% :\
It does just mean to 'rotate^2(u)'. According to p.17 of Lect.III, it must be \
to:
Does "double rotation" just mean "rotate^2(u)"? %toggle% :\
No, it is not the same thing. According to p.17 of Lect.III, it must be \
October 06, 2013, at 07:55 PM EST by 128.122.253.212 -
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This is an open-book exam, but not open-computer or electronic devices (or calculators).
to:
# This is an open-book exam, but not open-computer or electronic devices (or calculators).
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In terms of topics, you are technically responsible for everything up to
to:
# In terms of topics, you are technically responsible for everything up to
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To ensure adequate coverage, we will have a section of short questions.
to:
# To ensure adequate coverage, we will have a section of short questions.

# Here are some technical remarks, based on your questions:

'''What is a 'double rotation'?''' %toggle% :\
It does just mean to 'rotate^2(u)'. According to p.17 of Lect.III, it must be \
either zig-zag or zag-zig. But zig-zig or zag-zag do not count as 'double rotation'. \
Of course, all four cases comes under 'rotate^2(u)'.
October 06, 2013, at 07:51 PM EST by 128.122.253.212 -
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This will be in class, on Oct 10.

Get a sample copy of a past midterm exam from NYU Classes, under resources.
to:
# This will be in class, on Oct 10.

# Get a sample copy of a past midterm exam from NYU Classes, under resources.
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To ensure adequate coverage, we will have a section of short questions.
October 04, 2013, at 08:31 PM EST by 128.122.253.228 -
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We will give you more guidance soon.
to:
This is an open-book exam, but not open-computer or electronic devices (or calculators).
Sorry, if you want the lecture notes, you must print a copy.

In terms of topics, you are technically responsible for everything up to
the lecture on Oct 8. That means the first 6 Lectures.
But the first 3 Lectures will be emphasized, especially on topics
in the lecture and in the homework.
October 04, 2013, at 07:25 PM EST by 128.122.253.228 -
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Get a sample copy of a past midterm exam from NYU Classes, under resources.
October 02, 2013, at 10:23 AM EST by 128.122.253.212 -
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We will give you more guidance soon.
to:
We will give you more guidance soon.

!! Final Exam

This will be on Dec 19, in usual classroom 312, from 3:30-7:30 pm
.
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(:title Assignment Page :)

Assignments are either Homework Assignments or Reading Assignments.

!! Exam Page
to:
(:title Exam Page :)
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(:title Assignment Page :)

Assignments are either Homework Assignments or Reading Assignments.

!! Exam Page


(:if false:)
Your homework assignments are found in the following pdf file:

* Homework assignment file: [[(Attach:) coming-soon.pdf]].

* Homework solution file: [[(Attach:) hw_sol.pdf]].

(:if end:)

!! Midterm Exam

This will be in class, on Oct 10.

We will give you more guidance soon.