Predicate Logic and Popular Culture (Part 40): Sesame Street

Let $L(x,y)$ be the proposition “ $x$ is like $y$ .” Translate the logical statement

$\exists x (\forall y(x \ne y \Longrightarrow \lnot L(x,y)) \land \forall y \forall z((x \ne y \land x \ne z) \Longrightarrow L(y,z)))$ ,

where the domain is all things being displayed.

The clunky way of translating this into English is, “There exists one thing that is not like all of the other things, and everything else besides that one thing is like everything else besides that one thing”… which has been learned by generations of American pre-schoolers on Sesame Street.

Context: Part of a discrete mathematics course includes an introduction to predicate and propositional logic for our math majors. As you can probably guess from their names, students tend to think these concepts are dry and uninteresting even though they’re very important for their development as math majors.

In an effort to making these topics more appealing, I spent some time mining the depths of popular culture in a (likely futile) attempt to make these ideas more interesting to my students. In this series, I’d like to share what I found. Naturally, the sources that I found have varying levels of complexity, which is appropriate for students who are first learning prepositional and predicate logic.

When I actually presented these in class, I either presented the logical statement and had my class guess the statement in actual English, or I gave my students the famous quote and them translate it into predicate logic. However, for the purposes of this series, I’ll just present the statement in predicate logic first.

Predicate Logic and Popular Culture (Part 39): Taylor Swift

When teaching discrete mathematics, I’ll use today’s simple example to begin the section of propositional and predicate logic… it never fails to make my students chuckle.

Let $p$ be the proposition “We are getting back together.” Express the negation $\lnot p$ in ordinary English.

I’ll use this example to illustrate that the negation is simply “We are not getting back together,” without any need for extra emphasis or amplification… unlike the incredibly catchy Taylor Swift song.

Predicate Logic and Popular Culture (Part 38): The Blues Brothers

Let $N(x,y)$ be the proposition “ $x$ needs to love $y$ .” Translate the logical statement

$\forall x \exists y N(x,y)$ ,

where the domain is all people.

The clunky way of translating this into English is, “For every person, there exists a person who the first person needs to love.” But it sounds a lot better when sung by the Blues Brothers.

Predicate Logic and Popular Culture (Part 37): The Lord of the Rings

Let $L(x)$ be the proposition “ $x$ will love me,” and let $D(x)$ be the proposition “ $x$ will despair.” Translate the logical statement

$\forall x (L(x) \land D(x))$ ,

where the domain is all people.

This is one of the Galadriel’s predictions of the future had she accepted the One Ring from Frodo Baggins.

Predicate Logic and Popular Culture (Part 36): Hamlet

Let $R(x)$ be the proposition “ $x$ is rotten,” and let $D(x)$ be the proposition “ $x$ is in Denmark.” Translate the logical statement

$\exists x(R(x) \land D(x))$ ,

where the domain is all things.

The clunky way of translating this into English is, “There exists something that is rotten and in Denmark,” but the same thought is more dramatic when recited by it sounds better when recited by Marcellus at the start of Hamlet.

Predicate Logic and Popular Culture (Part 35): Elvis

Let $Y(x)$ be the proposition “You are $x$ .” Express the logical statement

$Y(\hbox{a hound dog}) \land \forall x(x \ne \hbox{a hound dog} \Rightarrow \lnot Y(x))$

into ordinary English, where the domain for $x$ are personal attributes.

Perhaps the shortest way to write this would be “You are only a hound dog,” but it’s much catchier when sung by Elvis.

Predicate Logic and Popular Culture (Part 34): The Beach Boys

Let $W(x,y)$ be the proposition “I wish that $x$ could be $y$ .” Translate the logical statement

$\forall x W(x, \hbox{a California girl})$

into plain English, where the domain for $x$ is all girls.

The simple way to translate this statement is “I wish that all girls could be California girls,” nearly matching the chorus of this classic by the Beach Boys.

Predicate Logic and Popular Culture (Part 33): The Eagles

Let $H(x,y,t)$ be the proposition “ $x$ hurts $y$ at time $t$ .” Translate the logical statement

$\exists x \exists y \exists t (0 \le t \le T \land H(x,y,t))$

into plain English, where the domain for $x$ and $y$ are all people, the domain for $t$ is all times, time $0$ is now, and time $T$ is when the night is through.

The simple way to translate this statement is “There are two people so that the first person will hurt the second person at some time between now and when the night is through.” A somewhat briefer way of expressing this thought is made in the first line of this popular song by The Eagles.

Predicate Logic and Popular Culture (Part 32): The Rolling Stones

Let $p$ be the proposition “I can get satisfaction.” Translate the logical statement $\lnot p$ into plain English.

The simple way to translate this statement is “I cannot get satisfaction.” The popular, though grammatically incorrect, way of expression this sentiment was made popular by the Rolling Stones.

Part of a discrete mathematics course includes an introduction to predicate and propositional logic for our math majors. As you can probably guess from their names, students tend to think these concepts are dry and uninteresting even though they’re very important for their development as math majors.

Engaging students: Approximating data by a straight line

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission again comes from my former student Esmerelda Sheran. Her topic, from Algebra: approximating data by a straight line.

A.2) How could you as a teacher create an activity or project that involves your topic?

If I created an activity for my class over approximating data by using a straight line I would make sure the type of data, they use is something that is relevant or interesting in the student’s lives. I would have the students work in pairs and choose the data they would work with out of three sets of data I have chosen. Examples of the choices of data would be the relationships between interceptions and wins for NFL teams, car accidents and age, or attendance and GPA (in college/universities). Using the data they chose the students would first take an educated guess of how the graph would look like, draw the scatter plot associated with the data, and compare their guess to the actual graph. At that point the students would try to identify the parent function (xb+c, mx+b, ab, ln(x) etc.) that the data is most similar to or if the data even has correlation. They would then draw what they believed the best fit line would look like on the scatterplot which they would compare to the linear regression once they calculated it on a graphing calculator. I would hope that this activity would be interesting due to the data being real and relatable as well as it being a way to connect parent functions and statistical data.

D.1) What interesting things can you say about the people who contributed to the discovery and/or the development of this topic?

Two of the main collaborators of linear regression are Sir Francis Galton and Karl Pearson. Galton was the discoverer of the linear regression and Pearson further elaborated on Galton’s ideas. Linear regression actually came to be because of sweet peas, Galton was studying heredity in sweet peas and formulated linear regression to aid him in studying the relations he found in his studies. Galton was much more than a hereditist, he was a geologist, meteorologist, tropical explorer, founder of differential psychology, inventor of fingerprint identifications, and an author. A few more interesting things about Galton is that he was knighted, he was accused of promoting eugenics, he was British and he was a half cousin of Charles Darwin. If you were wondering what “eugenics” is, it is the idea of planned breeding of humans through selectively breeding and sterilization. Galton once said, “… I object to pretensions of natural equality.” Being that Galton studied heredity it is no wonder that he felt that some physical/mental/emotional attributes where superior and that humans would benefit from having the “best” genes. Unfortunately for Galton eugenics was frowned upon and he was attacked for promoting it. I think that students would find Galton extremely interesting because of his wide variety of interests.

Karl Pearson, although not as complex as Galton had a few attributes that I feel would interest students. Pearson did not have a childhood that would be considered normal in modern day. Pearson was homeschooled up until he turned nine, and then he went to London alone to study at the University of College School. After he received his degrees and studied physics, metaphysics and Darwinism, Pearson developed his own view in social Darwinism. The social beliefs, he developed led him to changing his name from Carl to Karl.

E.1) How can technology be used to effectively engage students with this topic?

Technology in the classroom has and always will be an effective way to engage students if used correctly. To engage my students to learn how to approximated data with a straight line I would use excel, a smartboard, or the khan academy website. Excel is a useful piece of technology that is underappreciated by the average Joe. With a set of data you can record the relationships and then use the tools to create a scatterplot and then find the linear regression line on the graph.

Using a smartboard in the classroom is effective because it is new technology that is very special and kind of rare. Using smartboard to graph the points of data and then drawing an approximated regression line is highly kinesthetic and gives hands-on experiences instead of just typing in number and getting a calculated result that required almost no brain power. Kinesthetically moving their arms up, down, or side to side helps the students get a feel for the variation and relations between the data and drawing a best fit line themselves help the student understand the data on a different level. The Khan Academy website is a great resource for being introduced and even mastering the concept of linear regression because of the different activities available. For visual and auditory learners, there are a series of videos that explain approximating data by linear regression as well as how to be the most accurate when approximating. Similarly, there is an activity for kinesthetic learners in which they can move a line around to see which line seems most like the best fit line. It is beneficial from an instructor to use this website to help students of all learning types.

References

http://www.mirror.co.uk/news/uk-news/elderly-priest-found-dead-after-5099110

https://www.dartmouth.edu/~matc/math5.geometry/unit2/unit2.html

http://geomhistory.com/home.html

http://www.americanegypt.com/feature/cities/chichenitza/castillo_shadow.htm

https://explorable.com/greek-geometry