This chapter is about
the different types of knots and its components. The general definition for a
knot is a closed curve that is embedded in a three dimensional space and it is
usually modeled with rope. The study of knots is a mix of different mathematics
such as algebra, geometry, group theory, matrix theory, number theory, and
more. One of the simplest knots is the trefoil knot which is when the ends of
the rope are joined. The reason that it would be the simplest knot is because
it can be diagrammed with a minimum of three crossings. The next simplest knot
after the trefoil knot is the figure eight with four crossings. There are many
ways to divide knots into different classes. One of the ways is alternating and
non-alternating. Alternating knots can be diagrammed so that it is possible to
go over and under the crossings. Another way of division is prime and composite
knots. Prime knots cannot be manipulated to make two or more separated knots.
The last basic binary division is called the invertible and the non-invertible
knots. Invertible is being able to manipulate the rope so that the structure
stays the same but the arrows of direction point the other way. A pretzel knot,
on the other hand, has no crossings which proved that all pretzel knots are
noninvertible if the crossing numbers are distinct odd integers with absolute
values that are greater than one.
In L. Kauffman’s “Knots and Physics” book, she was using a
lot of examples to show the different types of knots that there were. She wasn’t
using a small variety and I would have wished that Gardner would have included
more examples such as a clove hitch and a bowline. In Kauffman’s book she also
explained the physics behind the knots not just the mathematics, which is what
I wished that Gardner would have included along with all of the different types
of mathematics. Friction and tension seem to be some of the main components in
making the knot form. While it would have been cool to see all of the different
types of knots in the book, I am glad that Gardner didn’t put in a step-by-step
for every single structure. Some of the structures are basic and other make you
want to think but as I was reading Kauffman’s book I wanted to try to solve the
knots myself but it was a bit hard to do so since she included the instructions
in both the writing and the images.
In the book “Introduction to Knot Theory” by R.H.
Crowell and R.H. Fox, there is a lot of explanation for the mathematics behind
the knots. Gardner briefly talks about the mathematics but he does not go into
greater detail about how mathematics can be used to form knots or to work with
knots in general. As a reader, I would wish for more information regarding how
exactly mathematics is involved. I am glad that Gardner didn’t include anything
about wild knots because as I was reading about wild knots in Crowell and Fox’s
book, it made me very confused about the wild knots and what their purpose is
to the talk of knots.
In K. Murasugi’s “Knot Theory and Its Applications,” the
author goes in depth on what an actual knot is and the trefoil knot. I wished
that Gardner would have explained more about a knot itself rather than give a
brief explanation and jump onto different divisions. I would have also wanted
for Gardner to talk more about the trefoil knot since it is the simplest knot.
The short summary that Gardner provided made me a little confused about the
trefoil knot; however, Murasugi’s explanation was a bit longer and more in
depth and led me to understand more about the trefoil knot. One more thing that
I wished that Gardner had included was a better explanation of mirrored “images”
with knots that involve the different mathematics. I’m glad that Gardner
omitted parts about the elementary knot moves because that part of Murasugi’s
book confused me. There is a lot of mathematics being thrown into that one
concept of the elementary knot moves that was hard to follow.
This chapter,
overall, was very interesting to read and after reading more into the three
author’s works besides Gardner’s, it had made me want to further look into the
different types of knots that exist and how some of them are formed. I wanted
to try forming them on my own as well. It also had made me want to read more
into the more in-depth mathematics and the different formulas used to make
these knots.