homework 161

CS 161: Computer Security

Announcements:

• Homework 7 is due Friday, December 3 , 11:59 PM PT.
• Project 3 is due Friday, December 3 , 11:59 PM PT.

Instructors: Raluca Ada Popa and Nicholas Weaver

Lecture: Monday, Wednesday, Friday, 10:00 AM–11:00 AM PT, 100 Lewis and online

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Design and Analysis of Algorithms

Stanford University, Winter 2024

Instructors: Nima Anari and Moses Charikar

Time: Mon & Wed 10:30 am - 12:00 pm

Location: Skilling Auditorium

Course Description: This course will cover the basic approaches and mindsets for analyzing and designing algorithms and data structures. Topics include the following: Worst and average case analysis. Recurrences and asymptotics. Efficient algorithms for sorting, searching, and selection. Data structures: binary search trees, heaps, hash tables. Algorithm design techniques: divide-and-conquer, dynamic programming, greedy algorithms, amortized analysis, and randomization. Algorithms for fundamental graph problems: minimum-cost spanning tree, connected components, topological sort, and shortest paths. Possible additional topics: network flow and string searching.

Prerequisites: CS 106B or CS 106X; CS 103 or CS 103B; CS 109 or STATS 116.

Course Grade: The course grade will be based on the following components.

Staff Contact

Homework Logistics

• Homework is to be handed in via GradeScope.
• Due: Friday October 6 at 3pm.
• Problem Set
• IPython Notebook
• Solution Set
• Due: Friday October 13 at 3pm.
• LaTeX source
• Due: Friday October 20 at 3pm.
• Auxiliary .py file (put in same directory as HW3.ipynb when you run it).
• Due: Friday October 27 at 3pm.
• mystery A (pickle file)
• mystery B (pickle file)
• Due: Friday November 10 at 3pm.
• graphStuff.py (this is our CS161Graph implementation)
• All of the python code in a zip file
• Due: Sunday November 19 at 3pm. (NOTICE! There is an extension!)
• Due: Friday December 1 at 3pm

Please ensure that your password is at least 8 characters and contains each of the following:

• a special character: @$#!%*?&

• Show each step of your work and fully simplify each expression.
• Turn in your answers in class on a physical piece of paper.
• Staple multiple sheets together.
• Feel free to use Desmos for graphing.

Answer the following:

• In the expression \[-42(x^2 + 3)(x+3)^2 + 5(x+4)^4(x-3)^2\] in what context is the expression $(x^2 + 3)$ not considered a factor, even though it is visually next to a multiplication?
• In fraction property #5, which says \[\dfrac{ac}{bc} = \dfrac{a}{b}\] what does $c$ need to be in order to be cancelled out?
• Can I cross out the $x^2$ in \[\dfrac{x^2 + 1}{x^2 + 2}\] to get $\dfrac{1}{2}$? Give the reason why or why not.
• Can I cross out the $x - 1$ in \[\dfrac{(x-1)(x+2)}{(x-1)(x+3)}\] to get $\dfrac{x+2}{x+3}$? Give the reason why or why not.
• Can I cross out the $x - 1$ and $x + 3$ in \[\dfrac{(x-1)(x+2) + 4(x+3)}{(x-1)(x+3)}\] to get $\dfrac{x+2 + 4}{1}$? Give the reason why or why not.
• Your friend tries to simplify $(x + 3)(x + 2)$ by using the Distributive law: \[(x + 3)(x + 2) = x + 3 \cdot x + x + 3 \cdot 2\] What did they do incorrectly?
• How many factors is $2x$ comprised of?
• In the global context, is the expression \[2x + 3y^2\] comprised of terms or factors?
• In the global context, is the expression \[-x(x-2)(x+3)5\] comprised of terms or factors?
• Global context of numerator comprises of three terms
• Global context of denominator comprises of two terms
• Each term in the numerator contains two factors
• Each term in the denominator contains three factors
• $(-\infty, 1) \cup (1, 2) \cup (2, \infty)$
• $(-\infty, -6]\cup (2, 10)$
• $(-10, -4]\cup (4, \infty)$
• A student tries to simplify \[\dfrac{x^{-1} + y^{-1}}{4} = \dfrac{1}{4xy}\] Why are you not allowed to do this?
• A student tries to simplify \[\dfrac{x+3}{x + 2} \cdot 4 = \dfrac{x+3\cdot 4}{x+2} = \dfrac{x+12}{x+2}\] Which mathematical property was violated? Hint: parentheses were forgotten.
• $x^4 \cdot x^7$
• $\left(\dfrac{1}{2}\right)^{-1}$
• $\left[\dfrac{(x^3y^5)^4}{z^{-4}}\right]^0$
• $\left(\dfrac{x}{y}\right)^2 \cdot \left(\dfrac{y^2}{z}\right)^3$
• $\dfrac{xy^{-3}z}{(2x)^{-1}y^2z^{-2}}$
• $\dfrac{(x+1)(x+2)}{(x+1)^{-2}(x+2)^2(x+3)}$
• $\dfrac{\sqrt[3]{x^2}}{x^{2/3}}$
• $\dfrac{(-3)^4\sqrt{x}}{3^2\sqrt[3]{x}}$
• $(2x-1)^{\frac{2}{3}}(2x-1)^{-\frac{1}{3}}$
• $(-3x)^2(-4x(x-1))^2$
• $\left(\dfrac{x^8y^{-2}}{(x-1)(x+2)^2}\right)^{-1/2}$
• A student tries to simplify $x^2 + x^3$ by applying exponent laws. They write \[x^2 + x^3 = x^{2+3} = x^5\] Why is this incorrect?
• A student tries to simplify $x^2 \cdot x^3$ by applying exponent laws. They write \[x^2 \cdot x^3 = x^{2\cdot3} = x^6\] Why is this incorrect?
• A student tries to simplify $(a + b)^2$ by applying exponent laws. They write \[(a + b)^2 = a^2 + b^2\] Why is this incorrect?
• A student tries to simplify $(2x + \sqrt{x})^2$ by applying exponent laws. They write \[(2x + \sqrt{x})^2 = 2x + x\] State the two errors they made and why they are incorrect.
• True or false: Like terms are expressions which share the same factors, except possibly for the coefficient (the number).
• $3x^2$ and $4y$
• $3x^2$ and $4x$
• $x^3y$ and $4x^3y$
• $5(x+1)(x+2)$ and $-(x+1)(x+2)$
• $-100(3x-2)(4x^2+3)^2$ and $4(4x^2+3)^2(3x-2)$
• $(2x^2 + 3x) + (3x^3 + 2x)$
• $(x+1)(x-2)$
• $(x^2 + 2x + 1)(x-2)$
• $(1 - x)^2$
• $(x^6 - x^5) -2(x^4 - x^3) - x(x^2 - x)$
• $3(x+h)^2 - 1 - (3x^2 - 1)$
• $-2x^3 - x^2$
• $(x+3)^2(x-2) + (x+3)(x-2)^2$
• $x^2 + 5x + 6$
• $x^2 + 13x + 12$
• $2x^2 + 7x + 3$
• $2x^2(x-1) + 7x(x-1) + 3(x-1)$
• $4a^2 - 9b^2$
• $(x^2 + 1)^2 - 7(x^2 + 1) + 10$
• $x^3 + 4x^2 + x + 4$
• Suppose there is a variable $x$ which is associated with a value $f(x)$. I find that two different inputs give the same evaluation. In particular, I find $x = -2$ and $x = 2$ have $f(-2) = f(2)$. Is $f(x)$ a function?
• Suppose I have an expression $f(x)$ and I find one input which gives two different evaluations. In particular, I find that $x = 2$ spits out $f(2) = 5$ and $f(2) = 3$. Is $f$ a function?
• Suppose there is an expression \[f(x) = \dfrac{(a + h)(b+h) + x}{(a+h)^3 - 5}\] Am I allowed to cancel out the $a+h$'s to get \[\dfrac{x}{(a+h)^2 - 5}\] If I am not, when am I allowed to cancel in this fashion?
• $x + \dfrac{3}{x}$
• $\dfrac{x+2}{x+1} + \dfrac{1}{x+3}$
• $\dfrac{1}{\sqrt{x}} + \dfrac{1}{\sqrt{x + h}}$
• $\sqrt{x+2} - \dfrac{1}{\sqrt{x+2}}$
• $\dfrac{x + 1}{\frac{x + 2}{x + 3}}$
• $x^{\frac{2}{3}}\cdot x^3$
• $(x+1)^8(x+1)^5$
• $\dfrac{x(x + 3)^2 + x(x-1)}{x}$
• $(x^2 + 3x^6)^{3/4}(x^2 + 3x^6)^{\frac{1}{2}}$
• $(4x+3)^{-2}(x+1)$
• When finding the domain of a function, what are the two types of inputs we need to exclude?
• Find $f(1), f(-a), f(x+h), f(x + h) - f(x)$ and fully expand each expression.
• Suppose a function takes an input $x$ and sends this to $\frac{1}{x + 1}$. What is the domain of $f(x)$?
• Draw a coordinate plane and graph the functions $f(x) = x^2, g(x) = x^4$ and $h(x) = x^6$. What is similar between the graphs?
• Graph the function \[f(x) = \begin{cases}-x^2 & x \leq 3 \\ -x + 1 & x > 3\end{cases}\]
• Is the point $\left(\frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}}\right)$ on the unit circle? Show using calculations.
• What is the reference number $\bar{t}$? What is the range of values $\bar{t}$ is allowed to be?
• $t = \frac{3\pi}{2}$
• $t = \frac{2\pi}{3}$
• $t = \frac{5\pi}{6}$
• $t = -\frac{2\pi}{3}$
• $t = -\frac{9\pi}{4}$
• $t = 1000\pi + \frac{2\pi}{3}$
• $t = -83\pi + \frac{\pi}{3}$
• $t = \pi + 2\pi - 3\pi + \frac{4\pi}{3}$
• (skip) Find the six trigonometric functions of $t = \frac{2\pi}{3}$.
• (skip) Find the six trigonometric functions of $t = -\frac{5\pi}{6}$.
• Why is $\tan\left(\frac{\pi}{2}\right)$ undefined?

General Homework Information

Read Project 2025 to see how radically Donald Trump wants to change America

So that you’ll be in-the-know as to what authoritarianism looks like, seriously consider reading one research-based book per month for the next five months as pre-election homework..

• Steve Corbin is a professor emeritus of marketing at the University of Northern Iowa.

According to a May 15 NBC News report, there are a multitude of issues that voters must discern about Joe Biden, Donald Trump and the independent presidential candidates before voting on Nov. 5. Logically, the importance of each issue differs between and among America’s 161.4 million registered voters.

One issue missing from the NBC News report that has become a focal point of the Biden camp, Make America Great Again Republicans and third-party candidates is democracy vs. authoritarianism. Specifically, on Jan. 20, 2025, will the duly elected and inaugurated president of the United States keep America as a democracy that dates back to the 1630’s in the New England colonies, or will it be the start of changing the country to authoritarian fascism?

If you’ve not heard of Project 2025, it’s very worthy of your independent investigation. Project 2025 is a playbook specifically created for Donald Trump and his supporters to use in the first 180 days of Trump’s 2025-29 presidential administration. The far-right extremism-based Heritage Foundation proudly takes claim for facilitating the creation of the 887-page turning-democracy-into-an-authoritarian-country document.

Project 2025’s two editors had assistance from 34 authors, 277 contributors, a 54-member advisory board and a coalition of over 100 conservative organizations (including the American Legislative Exchange Council, the Heartland Institute, Liberty University, Middle East Forum, Moms for Liberty, the National Rifle Association, Pro-Life America and Tea Party Patriots).

Project 2025 is a serious endeavor, if Trump returns to the White House, to make America a fascist country. After all, on May 20, Trump posted a video on his Truth Social media account depicting his 2025-29 administration as a “Unified Reich.” (Hitler’s Third Reich occurred from 1933 to 1945.)

Download the Project 2025 document (it's linked from this essay) so you can check out the disconcerting manuscript that tells Trump what specifically to do from Jan. 20 to July 18, 2025, to convert America into an authoritarian regime.

The 30 chapters of Project 2025 are a daunting read . Project 2025 proposes, among a host of things, eliminating the Department of Education, eliminating the Department of Commerce, deploying the US military whenever protests erupt, dismantling the FBI and Department of Homeland Security, removing sexual and gender protected discrimination and terminating diversity, equity, inclusion and affirmative action.

Additional mandates include: siphoning off billions of dollars of public school funding , funding private school choice vouchers, phasing out public education’s Title I program, gutting the nation’s free school meals program, eliminating the Head Start program, banning books and suppressing any curriculum that discusses the evils of slavery.

Project 2025 also calls for banning abortion ( which makes women second-class citizens ), restricting access to contraception, forcing would-be immigrants to be detained in concentration camps, eliminating Title VII and Title IX of the Civil Rights Act, recruiting 54,000 loyal MAGA Republicans to replace existing federal civil servants, and ending America’s bedrock principle that separates church from state.

A news story in Politico described Project 2025 as an authoritarian Christian nationalist movement and a path for the US to become an autocracy. Several legal experts have indicated implementing the 180-day manual would undermine the rule of law and the separation of powers.

As noted earlier, Project 2025 is worthy of your independent investigation. So that you’ll be in-the-know as to what authoritarianism looks like, seriously consider reading one research-based book per month for the next five months as pre-election homework. Here’s my suggested reading assignment:

June: "On Tyranny: 20 lessons from the 20th century," Timothy Snyder, 2017.

July: "Twilight of Democracy: The seductive lure of authoritarianism," Anne Applebaum, 2020. Chapters IV, V and VI get to the bottom line.

August: "Democracy Awakening: Notes on the State of America," Heather Cox Richardson, 2023.

September: "Attack from Within: How Disinformation is Sabotaging America," Barbara McQuade, 2024. The 1,717 reference citations proves this is well researched and an honest read.

October: "1984," George Orwell, 1949. Orwell’s novel shows Americans what life would be like under totalitarian and oppressive rule.

Reading even just one of these books will enable you to discern political candidate and party-based disinformation, misinformation and propaganda from truth, ready to vote on Nov. 5 and keep America a democracy.

Steve Corbin is a professor emeritus of marketing at the University of Northern Iowa. He receives no remuneration, funding or endorsement from any for-profit business, not-for-profit organization, political action committee or political party .

Serial Killer Quick Reference Guides

#1 Stranglers

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Sergei Ryakhovsky

The balashikha ripper, the hippopotamus,   active for 6 years (1988-1993) in russia, confirmed victims, possible victims.

• Serial Killer Profile
• Serial Killer Type
• General Information
• Characteristics
• Cognitive Ability
• Incarceration
• 8 Timeline Events
• Serial Killers Active During Spree
• Boolean Statistical Questions
• 12 Books Written About Sergei Ryakhovsky
• 3 External References

Internal References

Sergei Ryakhovsky (Sergei Vasilyevich Ryakhovsky) a Soviet-Russian serial killer known as the Balashikha Ripper and The Hippopotamus. Ryakhovsky was convicted for the killing of nineteen people in the Moscow area between 1988 and 1993. Ryakhovsky's mainly stabbed or strangulated his victims, he mutilated some bodies, mainly in the genital area. Allegedly Ryakhovsky carried out necrophilic acts on his victims and stole their belongings. Ryakhovsky standing 6’5" tall and weighting 286 pounds, gaining him the nickname, The Hippo. Sergei Ryakhovsky died on January 21st 2005 from untreated tuberculosis while serving his life sentence in prison.

Sergei Ryakhovsky Serial Killer Profile

Serial Killer Sergei Ryakhovsky (aka) the Balashikha Ripper, The Hippopotamus, was active for 6 years between 1988-1993 , known to have ( 19 confirmed / 19 possible ) victims. This serial killer was active in the following countries: Russia

Sergei Ryakhovsky was born on December 29th 1962 in Balashikha, Moscow Oblast, Soviet Union. He had a physically defect. During his education he had academic, social or discipline problems including being teased or picked on.

Sergei Ryakhovsky a necrophile male citizen of Russia.

Prior to his spree he had killed, commited crimes, and served time in jail.

In 1988 (Age 25/26) Sergei Ryakhovsky started his killing spree, during his crimes as a serial killer he was known to rob, commit acts of necrophilia , torture , strangle , rape , mutilate, and murder his victims.

He was arrested on April 13th 1993 (Age 30), sentenced to death by firing squad at a maximum-security penal colony in Solikamsk, Perm Oblast, Russia. He was convicted on charges of murder and other possible charges during his lifetime.

Sergei Ryakhovsky died on January 21st 2005 (Age 42), cause of death: natural causes, untreated tuberculosis at a maximum-security penal colony in Solikamsk, Perm Oblast, Russia.

Profile Completeness: 62%

Sergei Ryakhovsky has been listed on Killer.Cloud since November of 2016 and was last updated 4 years ago.

Sergei Ryakhovsky a known:

( 651 killers ) serial killer.

The unlawful killing of two or more victims by the same offender(s), in separate events. Serial Killer as defined by the FBI at the 2005 symposium.

( 308 killers ) RAPIST

Rape is usually defined as having sexual intercourse with a person who does not want to, or cannot consent.

( 60 killers ) NECROPHILIAC

Necrophilia, also called thanatophilia, is a sexual attraction or sexual act involving corpses. Serial Killer Necrophiliacs have been known to have sex with the body of their victim(s).

( 89 killers ) TORTURER

Torture is when someone puts another person in pain. This pain may be physical or psychological. Tourturers touture their victims.

( 251 killers ) STRANGLER

Strangulation is death by compressing the neck until the supply of oxygen is cut off. Stranglers kill by Strangulation.

Sergei Ryakhovsky Serial Killer Profile:

Updated: 2019-06-30 collected by killer.cloud, 8 timeline events of serial killer sergei ryakhovsky.

The 8 dates listed below represent a timeline of the life and crimes of serial killer Sergei Ryakhovsky. A complete collection of serial killer events can be found on our Serial Killer Timeline .

Back to top Serial Killers Active During

The following serial killers were active during the same time span as Sergei Ryakhovsky (1988-1993).

Jack Harold Jones 2 Victims during 13 Years

Gao chengyong 11 victims during 15 years, michael lee lockhart 3 victims during 2 years, pedro lopez 110 victims during 34 years, serial killers by active year, books that mention sergei ryakhovsky.

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External References

• Sergei Ryakhovsky on en.wikipedia.org , Retrieved on Sep 18, 2018 .
• Juan Ignacio Blanco , Sergei Vasilyevich RYAKHOVSKY on murderpedia.org , Retrieved on Sep 18, 2018 .
• Q372816 on www.wikidata.org , Retrieved on Oct 9, 2018 .

Sergei Ryakhovsky is included in the following pages on Killer.Cloud the Serial Killer Database

• #3 of 45[ Page 1 ] of Serial Killers with birthdays in December
• #10 of 60[ Page 1 ] of Serial Killer Necrophiliacs sorted by Confirmed Victims
• #10 of 29[ Page 1 ] of Serial Killers active in Russia
• #10 of 55[ Page 1 ] of Capricorn Serial Killers sorted by Confirmed Victims
• #11 of 89[ Page 1 ] of Serial Killer Torturers sorted by Confirmed Victims
• #27 of 250[ Page 2 ] of Serial Killer Stranglers sorted by Confirmed Victims
• #35 of 307[ Page 3 ] of Serial Killer Rapist sorted by Confirmed Victims
• #63 of 651[ Page 5 ] of serial killers sorted by Confirmed Victims
• #264 of 651[ Page 18 ] of serial killers sorted by Years Active
• #381 of 651[ Page 26 ] of serial killers sorted by Profile Completeness
• #516 of 651[ Page 35 ] of the A-Z List of Serial Killers