1.7.1 Relations: Video

MIT 6.042J Mathematics for Computer Science, Spring 2015
Instructor: Albert R. Meyer

License: Creative Commons BY-NC-SA

[oakmelon]

Great video, at 22:39, you will see the most common term "function" we used in computer science. A formal and concise definition

[codework-vber]

@10:47 "D ⊆ inverseR(J), " states ___the set of all students___ (denoted by D) happens to be a subset of ___the set of subjects that have registered students___ (denoted by inverseR(J)). It's *NOT* true because the set of all students (that is, D) includes/contains the element Adam but the set of subjects that have registered students (that is, inverseR(J)) does not include/contain some subject that has registered the student Adam -- D ⊆ inverseR(J) is {Jason, Joan, Yihui, Adam} ⊆ {Jason, Joan, Adam} and is False.

[sob]

so great for gaining a more intuitive understanding of what relations simply and fundamentally are!

[jjyeo]

At 10:45, why not use

D = R^(-1) (J)

to indicate that every student is registered for some subject?

It is against my intuition to use the "is a subset of" symbol because it is impossible for the domain of discourse to have fewer elements than the set of students who are registered for some subject.

[imad]

14:34 there is a missing arrow from TLP to Yihui

[Nick-uidr]

2:26 Adam looks more like me of school times. 😂

[ornicarornicar]

Something is troubling me...

At 6:53 the teacher uses the pipe symbol " | " and the dot symbol " . " but both are translated as " such as "
Is there a difference between those two symbols ?

[jonathansum]

Comparing the way that Khan Academy uses and the power point way, the only thing that students can feel is confusing.

[scottw]

Poor teaching way. He's actually reading the slides. If you can understand the materials in the reading notes, then you will not understand what he read.