Finished determinant calculation for linear system in proving lemma 3.

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Aaron Huber 2020-07-22 15:39:53 -04:00
parent cc0163b9a0
commit b3c492c97b
2 changed files with 77 additions and 12 deletions

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@ -26,6 +26,8 @@
\newcommand{\linsys}[1]{LS^{\graph{#1}}}
\newcommand{\lintime}[1]{LT^{\graph{#1}}}
\newcommand{\aug}[1]{AUG^{\graph{#1}}}
\newcommand{\mtrix}[1]{M_{#1}}
\newcommand{\dtrm}[1]{Det\left(#1\right)}
%PDBs
\newcommand{\ti}{TIDB}

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@ -402,6 +402,7 @@ The number of triangles in $\graph{k}$ for $k \geq 2$ will always be $0$ for the
\end{proof}
\qed
\AH{\LARGE \bf New material starts here.}
\subsection{Developing a Linear System}
In \cref{lem:qE3-exp} is the identity for $\rpoly(\prob,\ldots, \prob)$ when $\poly(\wElem_1,\ldots, \wElem_N) = q_E(\wElem_1,\ldots, \wElem_\numTup)^3$. (This lemma still needs a proof, but for now we will pretend the proof is there.)
@ -435,13 +436,13 @@ Rearrange terms into groups of those patterns that can be computed in $O(m)$ and
\end{equation*}
Let $\lintime{2}$ represent all the terms we wish to remove from $\linsys{2}$. Then, the following are true.
\begin{align*}
\lintime{2} &= -6\cdot\left(\numocc{\graph{1}}{\threedis} + \numocc{\graph{1}}{\twopathdis}\right)\left(\prob^2 - \prob^3\right) - 4 \cdot \numocc{\graph{1}}{\oneint}\left(\prob^2 - \prob^3\right) + 2\cdot \numocc{\graph{1}}{\twopath}\prob^2\\
\linsys{2'} = \linsys{2} -\lintime{2} &= -\pbrace{2 \cdot \numocc{\graph{1}}{\tri} + 4 \cdot \numocc{\graph{1}}{\threepath} + 2 \cdot \numocc{\graph{1}}{\threepath}}\left(\prob^2 - \prob^3\right)\\
\aug{2'} = \aug{2} - \lintime{2} &= \frac{\rpoly(\prob,\ldots, \prob)}{6\prob^3} - \frac{\numocc{\graph{2}}{\ed}}{6\prob} - \numocc{\graph{2}}{\twopath} - \numocc{\graph{2}}{\twodis}\prob - \numocc{\graph{2}}{\oneint}\prob - \big(\numocc{\graph{2}}{\twopathdis} + \numocc{\graph{2}}{\threedis}\big)\prob^2 + \\
&6\cdot\left(\numocc{\graph{1}}{\threedis} + \numocc{\graph{1}}{\twopathdis}\right)\left(\prob^2 - \prob^3\right) + 4 \cdot \numocc{\graph{1}}{\oneint}\left(\prob^2 - \prob^3\right) - 2\cdot \numocc{\graph{1}}{\twopath}\prob^2\\
\implies \aug{2'} &= \linsys{2'}
\end{align*}
\begin{align}
\lintime{2} &= -6\cdot\left(\numocc{\graph{1}}{\threedis} + \numocc{\graph{1}}{\twopathdis}\right)\left(\prob^2 - \prob^3\right) - 4 \cdot \numocc{\graph{1}}{\oneint}\left(\prob^2 - \prob^3\right) + 2\cdot \numocc{\graph{1}}{\twopath}\prob^2\nonumber\\
\linsys{2'} = \linsys{2} -\lintime{2} &= -\pbrace{2 \cdot \numocc{\graph{1}}{\tri} + 4 \cdot \numocc{\graph{1}}{\threepath} + 2 \cdot \numocc{\graph{1}}{\threepath}}\left(\prob^2 - \prob^3\right)\label{eq:LS-G2'}\\
\aug{2'} = \aug{2} - \lintime{2} &= \frac{\rpoly(\prob,\ldots, \prob)}{6\prob^3} - \frac{\numocc{\graph{2}}{\ed}}{6\prob} - \numocc{\graph{2}}{\twopath} - \numocc{\graph{2}}{\twodis}\prob - \numocc{\graph{2}}{\oneint}\prob - \big(\numocc{\graph{2}}{\twopathdis} + \numocc{\graph{2}}{\threedis}\big)\prob^2 +\nonumber \\
&6\cdot\left(\numocc{\graph{1}}{\threedis} + \numocc{\graph{1}}{\twopathdis}\right)\left(\prob^2 - \prob^3\right) + 4 \cdot \numocc{\graph{1}}{\oneint}\left(\prob^2 - \prob^3\right) - 2\cdot \numocc{\graph{1}}{\twopath}\prob^2\nonumber\\
\implies \aug{2'} &= \linsys{2'}\nonumber
\end{align}
We now have a linear equation in terms of $\graph{1}$ for $\graph{2}$ where $\linsys{2'}$ is the linear combination and $\aug{2}$ is the augmented side of the matrix, or the constant value, since all of the terms in $\aug{2}$ can be solved in $O(m)$ time.
@ -460,12 +461,74 @@ Equation \ref{eq:LS-G3-sub} follows from simple substitution of all lemma identi
Collecting terms we would like to send to the other side, the following equations are true,
\begin{align}
\lintime{3} =& \pbrace{- 24 \cdot \left(\numocc{\graph{1}}{\twopathdis} + \numocc{\graph{1}}{\threedis}\right) - 20 \cdot \numocc{\graph{1}}{\oneint} - 4\cdot \numocc{\graph{1}}{\twopath} - 6 \cdot \numocc{\graph{1}}{\twodis}}\left(\prob^2 - \prob^3\right) + \pbrace{\numocc{\graph{1}}{\ed}\prob + 2 \cdot \numocc{\graph{1}}{\twopath}}\prob\nonumber\\
\linsys{3'} =& \linsys{3} - \lintime{3} = \pbrace{- 18 \cdot \numocc{\graph{1}}{\tri} - 21 \cdot \numocc{\graph{1}}{\threepath} - 3 \cdot \numocc{\graph{1}}{\threedis}}\left(p^2 - p^3\right)\nonumber \\
\aug{3'} =& \aug{3} - \lintime{3} = \frac{\rpoly(\prob,\ldots, \prob)}{6\prob^3} - \frac{\numocc{\graph{3}}{\ed}}{6\prob} - \numocc{\graph{3}}{\twopath} - \numocc{\graph{3}}{\twodis}\prob - \numocc{\graph{3}}{\oneint}\prob - \big(\numocc{\graph{3}}{\twopathdis} + \numocc{\graph{3}}{\threedis}\big)\prob^2 + \\
\linsys{3'} =& \linsys{3} - \lintime{3} = \pbrace{- 18 \cdot \numocc{\graph{1}}{\tri} - 21 \cdot \numocc{\graph{1}}{\threepath} - 3 \cdot \numocc{\graph{1}}{\threedis}}\left(p^2 - p^3\right)\label{eq:LS-G3'} \\
\aug{3'} =& \aug{3} - \lintime{3} = \frac{\rpoly(\prob,\ldots, \prob)}{6\prob^3} - \frac{\numocc{\graph{3}}{\ed}}{6\prob} - \numocc{\graph{3}}{\twopath} - \numocc{\graph{3}}{\twodis}\prob - \numocc{\graph{3}}{\oneint}\prob - \big(\numocc{\graph{3}}{\twopathdis} + \numocc{\graph{3}}{\threedis}\big)\prob^2 + \nonumber\\
& \pbrace{24 \cdot \left(\numocc{\graph{1}}{\twopathdis} + \numocc{\graph{1}}{\threedis}\right) + 20 \cdot \numocc{\graph{1}}{\oneint} + 4\cdot \numocc{\graph{1}}{\twopath} + 6 \cdot \numocc{\graph{1}}{\twodis}}\left(\prob^2 - \prob^3\right) - \pbrace{\numocc{\graph{1}}{\ed}\prob + 2 \cdot \numocc{\graph{1}}{\twopath}}\prob\nonumber\\
&\implies \aug{3'} = \linsys{3'}
&\implies \aug{3'} = \linsys{3'}\nonumber
\end{align}
We now have a linear system consisting of three linear combinations, for $\graph{1}, \graph{2}, \graph{3}$ in terms of $\graph{1}$.
We now have a linear system consisting of three linear combinations, for $\graph{1}, \graph{2}, \graph{3}$ in terms of $\graph{1}$. To make it easier, use the following variable representations: $x = \numocc{\graph{1}}{\tri}, y = \numocc{\graph{1}}{\threepath}, z = \numocc{\graph{1}}{\threedis}$. Using $\linsys{2'}$ and $\linsys{3'}$, \cref{eq:LS-G2'}, \cref{eq:LS-G3'} respectively, the following matrix is obtained,
\[ \mtrix{\rpoly} = \begin{pmatrix}
x & (\prob)y & z(\prob^2 - \prob^3)\\
-2(\prob^2 - \prob^3)x & -4(\prob^2 - \prob^3)y & -2(\prob^2 - \prob^3)z\\
-18(\prob^2 - \prob^3)x & -21(\prob^2 - \prob^3)y & -3(\prob^2 - \prob^3)z
\end{pmatrix}.\]
Now we seek to show that all rows of the system are indeed independent.
Now we seek to show that all rows of the system are indeed independent.
The method of minors can be used to compute the determinant, $\dtrm{\mtrix{\rpoly}}$, giving
\begin{equation*}
\begin{vmatrix}
x & (\prob)y & z(\prob^2 - \prob^3)\\
-2(\prob^2 - \prob^3)x & -4(\prob^2 - \prob^3)y & -2(\prob^2 - \prob^3)z\\
-18(\prob^2 - \prob^3)x & -21(\prob^2 - \prob^3)y & -3(\prob^2 - \prob^3)z
\end{vmatrix}
=
\begin{vmatrix}
-4(\prob^2 - \prob^3) & -2(\prob^2 - \prob^3)\\
-21(\prob^2 - \prob^3) & -3(\prob^2 - \prob^3)
\end{vmatrix}
~ - ~ \prob~ \cdot
\begin{vmatrix}
-2(\prob^2 - \prob^3) & -2(\prob^2 - \prob^3)\\
-18(\prob^2 - \prob^3) & -3(\prob^2 - \prob^3)
\end{vmatrix}
+ ~(\prob^2 - \prob^3)~ \cdot
\begin{vmatrix}
-2(\prob^2 - \prob^3) & -4(\prob^2 - \prob^3)\\
-18(\prob^2 - \prob^3) & -21(\prob^2 - \prob^3)
\end{vmatrix}.
\end{equation*}
Compute each RHS term starting with the left and working to the right,
\begin{equation}
-4(\prob^2 - \prob^3)\cdot -3(\prob^2 - \prob^3) - \left(-21(\prob^2 - \prob^3) \cdot -2(\prob^2 - \prob^3)\right) =
12(\prob^2 - \prob^3)^2 - 42(\prob^2 - \prob^3)^2 = -30(\prob^2 - \prob^3)^2.\label{eq:det-1}
\end{equation}
The middle term then is
\begin{equation}
-\prob\left(-2(\prob^2 - \prob^3)\cdot -3(\prob^2 - \prob^3)\right) - \left(-18(\prob^2 - \prob^3) \cdot -2(\prob^2 - \prob^3)\right) =
-\prob\left(6\cdot (\prob^2 - \prob^3)^2 - 36(\prob^2 - \prob^3)^2\right) = -\prob\left(-30(\prob^2 - \prob^3)^2\right).\label{eq:det-2}
\end{equation}
Finally, the rightmost term,
\begin{equation}
\left(\prob^2 - \prob^3\right) \left(-2(\prob^2 - \prob^3)\cdot -21(\prob^2 - \prob^3)\right) - \left(-18(\prob^2 - \prob^3) \cdot -4(\prob^2 - \prob^3)\right) = \left(\prob^2 - \prob^3\right)\left(42\cdot (\prob^2 - \prob^3)^2 - 72(\prob^2 - \prob^3)^2\right) = \left(\prob^2 - \prob^3\right)\left(-30(\prob^2 - \prob^3)^2\right).\label{eq:det-3}
\end{equation}
Putting \cref{eq:det-1}, \cref{eq:det-2}, \cref{eq:det-3} together, we have,
\[\dtrm{\mtrix{\rpoly}} = -30(\prob^2 - \prob^3)^2-\prob\left(-30(\prob^2 - \prob^3)^2\right) + \left(\prob^2 - \prob^3\right)\left(-30(\prob^2 - \prob^3)^2\right)\]
Expanding out $\left(\prob^2 - \prob^3\right)^2$ gives
\begin{equation*}
\dtrm{\mtrix{\rpoly}} = -30\left(\prob^4 - 2\prob^5 + \prob^6\right)-\prob\left(-30\left(\prob^4 - 2\prob^5 + \prob^6\right)\right) + \left(\prob^2 - \prob^3\right)\left(-30\left(\prob^4 - 2\prob^5 + \prob^6\right)\right).
\end{equation*}
Further algebraic manipulations result in
\begin{align}
\dtrm{\mtrix{\rpoly}} &= \left(30\prob^4\right)\left(-1 + 2\prob - \prob^2\right) -\prob\left(-1\left(1 - 2\prob + \prob^2\right)\right) + \left(\prob^2 - \prob^3\right)\left(-1\left(1 - 2\prob + \prob^2\right)\right)\label{eq:det-factor}\\
&=\left(30\prob^4\right)\left(\left(-1 + 2\prob - \prob^2\right) + \left(\prob - 2\prob^2 + \prob^3\right) + \left( - \prob^2 + 2\prob^3 - \prob^4 + \prob^3 - 2\prob^4 + \prob^5\right)\right)\label{eq:det-mult}\\
&= \left(30\prob^4\right)\left(\prob^5 - 3\prob^4 + 4\prob^3 - 4\prob^2 + 3\prob - 1\right)\label{eq:det-combine}.
\end{align}
\cref{eq:det-factor} results from factoring out common terms. \cref{eq:det-mult} is the case when multiplying terms in the right hand factor. We arrive at \cref{eq:det-combine} through a simple rearranging and combining of like terms.
The roots for \cref{eq:det-combine} are $p = 0, p = 1$, and $p = i$. Thus, we have proved the lemma for fixed $p \in (0, 1)$.