User:Leo algknt: Difference between revisions

From Drorbn
Jump to navigationJump to search
No edit summary
No edit summary
Line 3: Line 3:
'''Question 1.'''
'''Question 1.'''


A. Prove that the set of all 3-colourings of a knot diagram is a vector space over {\mathbb F}_3. Hence \lambda(K) is always a power of 3
A. Prove that the set of all 3-colourings of a knot diagram is a vector space over <math>{\mathbb F}_3</math>. Hence <math>\lambda(K)</math> is always a power of 3


Attempt: Let <math>D</math> be a knot diagram with <math>n</math> crossings. There are <math>n</math> arcs. Let <math>a_1, a_1, \ldots, a_n \in \mathbb{Z}/3\mathbb{Z}</math> represent the arcs. Now let <math>a,b,c \in \mathbb{Z}/3\mathbb{Z}</math> , with
Attempt: Let <math>D</math> be a knot diagram with <math>n</math> crossings. There are <math>n</math> arcs. Let <math>a_1, a_1, \ldots, a_n \in \mathbb{Z}/3\mathbb{Z}</math> represent the arcs. Now let <math>a,b,c \in \mathbb{Z}/3\mathbb{Z}</math> , with



$
a\wedge b =
<math>a\wedge b =


\left\{
\left\{
Line 15: Line 15:
c, & a\not= b
c, & a\not= b
\end{array}
\end{array}
\right.
\right.</math>
$


At each crossing we have a linear equation x
At each crossing we have a linear equation x
Line 23: Line 22:
Let
Let


B. Prove that \lambda(K) is computable in polynomial time in the number of crossings of K.
B. Prove that <math>\lambda(K)</math> is computable in polynomial time in the number of crossings of K.

Revision as of 00:13, 24 May 2018

Home Work 1

Question 1.

A. Prove that the set of all 3-colourings of a knot diagram is a vector space over . Hence is always a power of 3

Attempt: Let be a knot diagram with crossings. There are arcs. Let represent the arcs. Now let , with


At each crossing we have a linear equation x


Let

B. Prove that is computable in polynomial time in the number of crossings of K.