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\begin{document}
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{\LARGE{\bf Cheat Sheet $sl_2$-Portfolio}}\hfill(an implementation of the $sl_2$ portfolio)\hfill
\parbox[b]{2.5in}{\tiny
  \null\hfill\url{http://drorbn.net/AcademicPensieve/Projects/SL2Portfolio/}
  \newline\null\hfill
   modified \today, \currenttime
}

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\vspace{-8mm}

\begin{multicols}{2} \raggedcolumns

%\entry{170625}
{\bf $\calU_{\gamma\epsilon;\hbar}$ conventions.} \hfill \pinkt{``consolidate''}

$\pinkm{q=\bbe^{\hbar\gamma\epsilon}}$, $H=\langle a,x\rangle/(\yellowm{[a,x]=\gamma x})$ with
\[ \pinkm{A=\bbe^{-\hbar\epsilon a}}, \quad xA=qAx, \quad S_{\!H}(a,A,x)=(-a, A^{-1}, -A^{-1}x), \]
\[ \Delta_H(a,A,x)=(a_1+a_2, A_1A_2, x_1+A_1x_2) \]
and dual $H^\ast=\langle b, y\rangle/(\yellowm{[b,y]=-\epsilon y})$ with
\[ \pinkm{B=\bbe^{-\hbar\gamma b}}, \quad By=qyB, \quad S_{\!H^\ast}(b,B,y)=(-b, B^{-1}, -yB^{-1}), \]
\[ \Delta_{H^\ast}(b,B,y)=(b_1+b_2, B_1B_2, y_1B_2+y_2). \]

Pairing by $(a,x)^\ast=\hbar(b,y)$ ($\Rightarrow\langle B,A\rangle=q$) making $\langle y^lb^i,a^jx^k\rangle = \delta_{ij}\delta_{kl}\hbar^{-(j+k)}j![k]_q!$ so $R=\sum\frac{\hbar^{j+k}y^kb^j\otimes a^jx^k}{j![k]_q!}$.
Then $\calU=H^{\ast\text{\it cop}}\otimes H$
with $(\phi f)(\psi g) = \langle \psi_1S^{-1}f_3\rangle \langle \psi_3,f_1\rangle(\phi\psi_2)(f_2g)$ and
\[ S(y,b,a,x) = (-B^{-1}y, -b, -a, -A^{-1}x),\]
\[ \Delta(y,b,a,x) = (y_1+y_2B_1, b_1+b_2, a_1+a_2, x_1+A_1x_2).\]

With the central $t\coloneqq\epsilon a-\gamma b$, $\pinkm{T\coloneqq \bbe^{\hbar t}}=A^{-1}B$ get
\[ \yellowm{[a,y]=-\gamma y}, \quad \yellowm{[b,x]=\epsilon x},\quad \yellowm{xy-qyx=(1-TA^2)/\hbar}. \]
Cartan: $\theta(y, b, a, x)=(-B^{-1}T^{1/2}x, -b, -a, -A^{-1}T^{-1/2}y)$. (Suggesting that it may be better to redefine $y\to y'=\theta x=A^{-1}T^{-1/2}y$.)

At $\epsilon=0$, $\calU_{\hbar;\gamma 0}=\langle t,y,a,x\rangle/([t,\cdot]=0,\,[a,x]=\gamma x,\,[a,y]=-\gamma y,\,[x,y]=(1-T)/\hbar)$ with $\Delta(t,y,a,x)=(t_1+t_2,y_1+T_1y_2,a_1+a_2, x_1+x_2)$ and $\theta(y, b, a, x)=(-T^{-1/2}x, -b, -a, -T^{-1/2}y)$.

{\bf Working Hypothesis.} $(\hbar,t,y,a,x)$ makes a PBW basis.

{\bf Casimir.} $\omega=\gamma yx+\epsilon a^2-(t-\gamma\epsilon)a$, satisfies\ldots. Roland in \href{http://drorbn.net/AcademicPensieve/People/VanDerVeen/MixOrder@.pdf}{MixOrder.pdf}: Centrals are valuable; perhaps we should write everything in $CU/QU$ as $(x\vee y)\cdot$(functions of $a$)$\cdot$(centrals).

{\bf Scaling} with $\deg\colon\{\gamma,\epsilon,a,b,x,y\}\to 1,\,\{\hbar\}\to -2,\,\{t\}\to 2,\,\{\omega\}\to 3$.

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\vskip 2mm
{\bf Verification} (as in \href{http://drorbn.net/AcademicPensieve/Projects/PPSA/nb/Verification.pdf}{Projects/PPSA/Verification.nb}).
\vskip 1mm

\par\includegraphics[scale=\cellscale]{Snips/DocileQ-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/TD-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/CF-1.pdf}

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\par\includegraphics[scale=\cellscale]{Snips/SP-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/CU-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/QU-1.pdf}

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\ifnum \snip<5 \repeat

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{\bf Fear Not.} If $G=\bbe^{\xi x}y\bbe^{-\xi x}$ then $F = \bbe^{-\eta y}\bbe^{\xi x}\bbe^{\eta y}\bbe^{-\xi x} = \bbe^{-\eta y}\bbe^{\eta G}$ satisfies $\partial_\eta F=-yF+FG$ and $F_{\eta=0}=1$:

\par\includegraphics[scale=\cellscale]{Snips/tSW-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/Faddeev-1.pdf}

\par\includegraphics[scale=\cellscale]{Snips/R-1.pdf}

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\vskip 1mm
{\bf To do.}
$\bullet$~Consider renormalizing $x$ and $y$.
$\bullet$~Can everything be done at $\hbar=1$ defining a filtration by other means? That ought to be possible as the end results depend on $t/T$ and not on $\hbar$.
$\bullet$ Bound the degrees of the logoi!
$\bullet$ $r=\theta r$?
$\bullet$ $\theta$ is a global symmetry. Can it be ``gauged''?
$\bullet$ Global $\eta\to\psi$?

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{\bf Alternative Algorithms.}
\vskip 1mm

\par\includegraphics[scale=\cellscale]{Snips/AltLogos-1.pdf}

\vskip 1mm{\bf Asides.} \quad \includegraphics[scale=\cellscale]{Snips/Aside-1.pdf}

\vskip 2mm\par\includegraphics[scale=\cellscale]{Snips/Aside-2.pdf}

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{\bf $\calG\calD\calO$-Categories.} Given $\frakg$ with basis $B=\{x,y,\ldots\}$, consider the following diagram:
\[ \xymatrix@C=11.5mm{
  \bbQ=\hat\calU_{(q)}\left(\bigoplus_0\frakg\right)
    \ar[r]^<>(0.5)Z &
  \hat\calU_{(q)}\left(\frakg\right)
    \ar@/^/[r]^<>(0.5)\Delta &
  \hat\calU_{(q)}\left(\bigoplus_2\frakg\right)
    \ar@/^/[l]^<>(0.5)m \\
  \hat\calS\left(\emptyset\right)
    \ar[r]^<>(0.5)Z
    \ar[u] &
  \hat\calS\left(B\right)
    \ar@/^/[r]^<>(0.5)\Delta
    \ar@/^/[u]^{\bbO(xy\ldots\colon\cdot)}
    \ar@/_/[u]_{\bbO(yx\ldots\colon\cdot)}
    \ar@`{p+(-16,-16),p+(+16,-16)}^{\SW_{xy}} &
  \hat\calS\left(B_1,B_2\right)
    \ar@/^/[l]^<>(0.5)m
    \ar[u]_{\bbO(y_1x_1\ldots\otimes y_2x_2\ldots\colon\cdot)}
} \]
Hence $Z$, $\SW_{xy}$, $m$, $\Delta$, (and likewise $S$ and $\theta$) are morphisms in the {\em completion} of the monoidal category $\calF$ whose objects are finite sets $B$ and whose morphism are $\mor_\calF(B,B') \coloneqq \Hom_\bbQ\left(\calS(B)\to\calS(B')\right) = \calS\left(B^\ast,B'\right)$ (by convention, $x^\ast=\xi$, $y^\ast=\eta$, etc.). Ergo we need to {\em consolidate} (at least parts of) said completion.

{\bf Aside.} ``Consolidate'' means  ``give a finite name to an infinite object, and figure out how to sufficiently manipulate such finite names''. E.g., solving $f''=-f$ we encounter and set $\sum\frac{(-1)^kx^{2k}}{(2k)!}\leadsto\cos x$, $\sum\frac{(-1)^kx^{2k+1}}{(2k+1)!}\leadsto\sin x$, and then $\cos^2x+\sin^2x=1$ and $\sin(x+y)=\sin x\cos y+\cos x\sin y$.

{\bf Example.}

{\bf Example.} In $QU/(\epsilon^2=0)$ using the $yax$ order over $\bbQ\llbracket\hbar\rrbracket$, with $T=\bbe^{\hbar t}$, $\barT=T^{-1}$, $\calA=\bbe^{\gamma\alpha}$, and $\bcA=\calA^{-1}$,
\[
  R_{ij} = \bbe^{\hbar(y_ix_j-t_ia_j/\gamma)} \left(1+\epsilon\hbar\left(a_ia_j/\gamma-\gamma\hbar^2y_i^2x_j^2/4\right)\right)
  \in \calS(B_i,B_j),
\]
\begin{multline*}
  m = \bbe^{(\alpha _1+\alpha _2)a+\eta _2 \xi _1(1-T)/\hbar + (\xi_1\bcA_2 + \xi _2)x + (\eta_1+\eta_2\bcA_1) y} \left(1+\epsilon\lambda_m\right) \\
   \in \calS(B^\ast_1,B^\ast_2,B),
\end{multline*}
with {\footnotesize$\lambda_m = 2a\eta_2\xi_1T + \frac{1}{4}\gamma\eta_2^2\xi_1^2\left(3T^2-4T+1\right)/\hbar - \frac{1}{2}\gamma\eta_2\xi_1^2(3T-1)x\bcA_2 - \frac{1}{2}\gamma\eta_2^2\xi_1(3 T-1)y\bcA_1 + \gamma\eta_2\xi_1xy\hbar\bcA_1\bcA_2$},
\begin{multline*}
  \Delta = \bbe^{\tau(t_1+t_1)+\eta(y_1+T_1y_2)+\alpha(a_1+a_2)+\xi(x_1+x_2)}\left(1 + \epsilon\lambda_\Delta\right) \\
  \in \calS(B^\ast,B_1,B_2),
\end{multline*}
with {\scriptsize $\lambda_\Delta = -a_1\eta T_1y_2\hbar - a_1\xi x_2\hbar + \frac{1}{2}\gamma\eta^2T_1y_1y_2\hbar + \frac{1}{2}\gamma\xi^2 x_1 x_2 \hbar$}, and
\[
  S = \bbe^{-\tau t -\alpha a -\eta  \xi  (1-\barT)\calA/\hbar - \barT\eta  y \calA -\xi  x \calA}\left(1+\epsilon  \lambda_S\right)
  \in\calS(B^\ast,B),
\]
with {\footnotesize$\lambda_S =
    2\barT\calA a \eta  \xi
  - \barT\calA a \eta  y \hbar
  - a \xi  x \hbar \calA
  - \frac14 \gamma  \eta ^2 \xi ^2 \left(1-4\barT+3\barT^2\right)\calA^2/\hbar
  - \frac12\gamma  \eta ^2 y^2 \hbar\barT^2\calA^2
  - \frac12\gamma\eta^2\xi\barT(1-3\barT) y \calA^2
  + \gamma\eta  \xi(1-\barT)\calA
  - \frac12\gamma\eta\xi^2(1-3\barT) x \calA^2
  - \gamma  \eta \xi  x y \hbar \barT\calA^2
  + \gamma  \eta  y \hbar\barT\calA
  - \frac{1}{2} \gamma  \xi x^2 \hbar \calA^2
$}.

{\bf Problem.} Compute the likes of $m\act\Delta = \left(\left.m\right|_{b\to\partial_\beta}\Delta\right)_{\beta=0}$ and $(R_{12}R_{34})\act m^{13}_2 = \left(\left.(R_{12}R_{34})\right|_{b\to\partial_\beta}m^{13}_2\right)_{\beta=0}$.

A generic morphism:

\[ \input{GDOMorphism.pdf_t} \]

{\bf The Zipping Issue.}\hfill\includegraphics[width=0.8in]{zipper.png}\hfill\null

{\bf The Contraction Theorem.} If $P$ has a finite $\zeta$-degree and the $y$'s and the $q$'s are ``small'',
\[ \left\langle P(z_i,\zeta^j)\right\rangle_{(\zeta_i)}
  = \left.P\left(z_i,\overset{\leftrightarrow}{\partial}_{\!z_j}\right)\right|_{z_i=0},
\]
\[ \left\langle P(z_i,\zeta^j)\bbe^{\eta^iz_i+y_j\zeta^j}\right\rangle_{(\zeta_i)}
  = \left\langle P(z_i+y_i,\zeta^j)\bbe^{\eta^i(z_i+y_i)}\right\rangle_{(\zeta_i)},
\]
(proof: replace $y_j\to\hbar y_j$ and test at $\hbar=0$ and at $\partial_\hbar$), and
\begin{multline*}
  \left\langle P(z_i,\zeta^j)\bbe^{c+\eta^iz_i+y_j\zeta^j+q^i_jz_i\zeta^j}\right\rangle_{(\zeta_i)} \\
  = \det(\tilq)\left\langle
    P(\tilq_i^k(z_k+y_k),\zeta^j)\bbe^{c+\eta^i\tilq^k_i(z_k+y_k)}
  \right\rangle_{(\zeta_i)}
\end{multline*}
where $\tilq$ is the inverse matrix of $1-q$: $(\delta^i_j-q^i_j)\tilq^j_k=\delta^i_k$
(proof: replace $q^i_j\to\hbar q^i_j$ and test at $\hbar=0$ and at $\partial_\hbar$).

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{\bf Program} (as in \href{http://drorbn.net/AcademicPensieve/Projects/PPSA/nb/Verification.pdf}{Projects/PPSA/Verification.nb}).
\vskip 1mm

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