lie-algebras-and-their-representations

Source code for my notes on representations of semisimple Lie algebras and Olivier Mathieu's classification of simple weight modules

Commit
d9336d2c01b84402ffb17ec3a0987da1c5f73137
Parent
f02b089f3c69404e92749e6d114df5111908ce77
Author
Pablo <pablo-escobar@riseup.net>
Date

Changed the notation for the set of parameters for coherent families

Also changed the script-style font

Diffstat

2 files changed, 30 insertions, 32 deletions

Status File Name N° Changes Insertions Deletions
Modified preamble.tex 2 1 1
Modified sections/coherent-families.tex 60 29 31
diff --git a/preamble.tex b/preamble.tex
@@ -24,7 +24,7 @@
 \usepackage[T1]{fontenc}
 \usepackage[sc]{mathpazo}
 \renewcommand*\ttdefault{txtt}
-\usepackage[scr=esstix,cal=boondox]{mathalfa}
+\usepackage[scr=euler,cal=boondox]{mathalfa}
 \hypersetup{
   colorlinks,
   citecolor=black,
diff --git a/sections/coherent-families.tex b/sections/coherent-families.tex
@@ -147,11 +147,11 @@ Example~\ref{ex:sp-canonical-basis}. Also fix \(\rho = \sfrac{1}{2} \beta_1 +
 \end{proposition}
 
 \begin{definition}
-  We denote by \(\mathscr{Q}\) the set of the \(m \in (\sfrac{1}{2} +
+  We denote by \(\mathscr{B}\) the set of the \(m \in (\sfrac{1}{2} +
   \mathbb{Z})^n\) such that \(m_1 > m_2 > \cdots > m_{n - 1} > \pm m_n\). We
-  also consider the canonical partition \(\mathscr{Q} = \mathscr{Q}^+ \cup
-  \mathscr{Q}^-\) where \(\mathscr{Q}^+ = \{ m \in \mathscr{Q} : m_n > 0 \}\)
-  and \(\mathscr{Q}^- = \{ m \in \mathscr{Q} : m_n < 0\}\).
+  also consider the canonical partition \(\mathscr{B} = \mathscr{B}^+ \cup
+  \mathscr{B}^-\) where \(\mathscr{B}^+ = \{ m \in \mathscr{B} : m_n > 0 \}\)
+  and \(\mathscr{B}^- = \{ m \in \mathscr{B} : m_n < 0\}\).
 \end{definition}
 
 % TODO: Prove this
@@ -164,7 +164,7 @@ Example~\ref{ex:sp-canonical-basis}. Also fix \(\rho = \sfrac{1}{2} \beta_1 +
   \mExt(L(\mu))\) if, and only if \(m(\lambda)_i = m(\mu)_i\) for \(i < n\) and
   \(m(\lambda)_n = \pm m(\mu)_n\). In particular, the isomorphism classes of
   semisimple irreducible coherent \(\mathfrak{sp}_{2n}(K)\)-families are
-  parameterized by \(\mathscr{Q}^+\).
+  parameterized by \(\mathscr{B}^+\).
 \end{theorem}
 
 \section{Coherent \(\mathfrak{sl}_n(K)\)-families}
@@ -234,16 +234,14 @@ Example~\ref{ex:sl-canonical-basis}. Also fix \(\rho = \sfrac{1}{2} \beta_1 +
   + 1}\) is \emph{not} a positive integer.
 \end{proposition}
 
-% TODO: Change the notation for 𝓟 ? The paper on affine vertex algebras calls
-% this graph 𝓑
-% TODO: Explain the significance of 𝓟 + and 𝓟 -: these are the subsets whose
+% TODO: Explain the significance of 𝓑 + and 𝓑 -: these are the subsets whose
 % union corresponds to condition (i)
 \begin{definition}
-  We denote by \(\mathscr{P}\) the set of \(\mathfrak{sl}_n\)-sequences \(m\)
+  We denote by \(\mathscr{B}\) the set of \(\mathfrak{sl}_n\)-sequences \(m\)
   such that \(m_i - m_{i + 1}\) is a positive integer for all but a single \(i
-  < n\). We also consider the subsets \(\mathscr{P}^+ = \{m \in \mathscr{P} :
-  m_1 - m_2 \ \text{is \emph{not} a positive integer}\}\) and \(\mathscr{P}^- =
-  \{m \in \mathscr{P} : m_{n-1} - m_n \ \text{is \emph{not} a positive
+  < n\). We also consider the subsets \(\mathscr{B}^+ = \{m \in \mathscr{B} :
+  m_1 - m_2 \ \text{is \emph{not} a positive integer}\}\) and \(\mathscr{B}^- =
+  \{m \in \mathscr{B} : m_{n-1} - m_n \ \text{is \emph{not} a positive
   integer}\}\).
 \end{definition}
 
@@ -252,7 +250,7 @@ Example~\ref{ex:sl-canonical-basis}. Also fix \(\rho = \sfrac{1}{2} \beta_1 +
 % implies L(μ) is contained in 𝓔𝔁𝓽(L(λ)) - so that L(μ) is also bounded and
 % 𝓔𝔁𝓽(L(λ)) ≅ 𝓔𝔁𝓽(L(μ))
 \begin{definition}
-  Given \(m, m' \in \mathscr{P}\), say there is an arrow \(m \to m'\) if
+  Given \(m, m' \in \mathscr{B}\), say there is an arrow \(m \to m'\) if
   the unique \(i\) such that \(m_i - m_{i + 1}\) is not a positive integer is
   such that \(m' = \sigma_i \cdot m\).
 \end{definition}
@@ -261,8 +259,8 @@ It should then be obvious that\dots
 
 \begin{proposition}
   Let \(\lambda \notin P^+\) be such that \(L(\lambda)\) is bounded -- so that
-  \(m(\lambda) \in \mathscr{P}\) -- and suppose that \(\mu \in \mathfrak{h}^*\)
-  is such that \(m(\mu) \in \mathscr{P}\) and there is an arrow \(m(\lambda)
+  \(m(\lambda) \in \mathscr{B}\) -- and suppose that \(\mu \in \mathfrak{h}^*\)
+  is such that \(m(\mu) \in \mathscr{B}\) and there is an arrow \(m(\lambda)
   \to m(\mu)\). Then \(L(\mu)\) is also bounded and \(\mExt(L(\mu)) \cong
   \mExt(L(\lambda))\).
 \end{proposition}
@@ -278,7 +276,7 @@ all \(i \ne j\) or \(m_i = m_j\) for some \(i \ne j\), respectively. Similarly,
 \(\mathfrak{sl}_n\)-sequence \(m\) integral if \(m_i - m_j \in \mathbb{Z}\) for
 all \(i\) and \(j\).
 
-% TODO: Add notes on what are the sets W ⋅m ∩ 𝓟  : the connected component of
+% TODO: Add notes on what are the sets W ⋅m ∩ 𝓑  : the connected component of
 % a given element is contained in its orbit, but a given orbit may contain
 % multiple connected components. When m is regular and integral then its orbit
 % is the union of n connected components, but otherwise its orbit is precisely
@@ -287,11 +285,11 @@ all \(i\) and \(j\).
 % theorem? Perhaps it's best to create another lemma for this
 % TODO: Restate the notation for σ_i beforehand
 \begin{proposition}
-  The connected component of some \(m \in \mathscr{P}\) is given by the
+  The connected component of some \(m \in \mathscr{B}\) is given by the
   following.
   \begin{enumerate}
     \item If \(m\) is regular and integral then there exists\footnote{Notice
-      that in this case $m' \notin \mathscr{P}$, however.} a unique \(m' \in W
+      that in this case $m' \notin \mathscr{B}$, however.} a unique \(m' \in W
       \cdot m\) such that \(m_1' > m_2' > \cdots > m_n'\), in which case the
       connected component of \(m\) is given by
       \[
@@ -312,8 +310,8 @@ all \(i\) and \(j\).
         \end{tikzcd}
       \]
       for some unique \(i\), with \(\sigma_1 \cdots \sigma_i \cdot m' \in
-      \mathscr{P}^+\) and \(\sigma_{n-1} \cdots \sigma_i \cdot m' \in
-      \mathscr{P}^-\).
+      \mathscr{B}^+\) and \(\sigma_{n-1} \cdots \sigma_i \cdot m' \in
+      \mathscr{B}^-\).
 
     \item If \(m\) is singular then there exists unique \(m' \in W \cdot m\)
       and \(i\) such that \(m_1' > m_2' > \cdots > m_i' = m_{i + 1}' > \cdots >
@@ -335,8 +333,8 @@ all \(i\) and \(j\).
           \sigma_{n-1} \cdots \sigma_{i+1} \cdot m'            \lar &
         \end{tikzcd}
       \]
-      with \(\sigma_1 \cdots \sigma_{i-1} \cdot m' \in \mathscr{P}^+\) and
-      \(\sigma_{n-1} \cdots \sigma_{i+1} \cdot m' \in \mathscr{P}^-\).
+      with \(\sigma_1 \cdots \sigma_{i-1} \cdot m' \in \mathscr{B}^+\) and
+      \(\sigma_{n-1} \cdots \sigma_{i+1} \cdot m' \in \mathscr{B}^-\).
 
     \item If \(m\) is non-integral then there exists unique \(m' \in W \cdot
       m\) such that \(m_2' > m_3' > \cdots > m_n'\), in which case the
@@ -350,16 +348,16 @@ all \(i\) and \(j\).
           \sigma_{n-1} \cdots \sigma_1 \cdot m'      \lar &
         \end{tikzcd}
       \]
-      with \(m' \in \mathscr{P}^+\) and \(\sigma_{n-1} \cdots \sigma_1 \cdot m'
-      \in \mathscr{P}^-\).
+      with \(m' \in \mathscr{B}^+\) and \(\sigma_{n-1} \cdots \sigma_1 \cdot m'
+      \in \mathscr{B}^-\).
   \end{enumerate}
 \end{proposition}
 
-% TODO: Add pictures of parts of the graph 𝓟 ?
+% TODO: Add pictures of parts of the graph 𝓑 ?
 
-% TODO: Notice that this gives us that if m(λ)∈ 𝓟  then L(λ) is bounded: for λ
-% ∈ 𝓟 + ∪ 𝓟 - we stablish this by hand, and for the general case it suffices to
-% notice that there is always some path μ → ... → λ with μ ∈ 𝓟 + ∪ 𝓟 -
+% TODO: Notice that this gives us that if m(λ)∈ 𝓑  then L(λ) is bounded: for λ
+% ∈ 𝓑 + ∪ 𝓑 - we stablish this by hand, and for the general case it suffices to
+% notice that there is always some path μ → ... → λ with μ ∈ 𝓑 + ∪ 𝓑 -
 % TODO: Perhaps this could be incorporated into the discussion of the lemma
 % that characterizes the weights of sl(n) whose L is bounded
 
@@ -367,11 +365,11 @@ all \(i\) and \(j\).
 \begin{theorem}[Mathieu]
   Given \(\lambda, \mu \notin P^+\) with \(L(\lambda)\) and \(L(\mu)\) bounded,
   \(\mExt(L(\lambda)) \cong \mExt(L(\mu))\) if, and only if \(m(\lambda)\) and
-  \(m(\mu)\) lie in the same connected component of \(\mathscr{P}\). In
+  \(m(\mu)\) lie in the same connected component of \(\mathscr{B}\). In
   particular, the isomorphism classes of semisimple irreducible coherent
   \(\mathfrak{sl}_n(K)\)-families are parameterized by the set
-  \(\pi_0(\mathscr{P})\) of the connected components of \(\mathscr{P}\), as
-  well as by \(\mathscr{P}^+\).
+  \(\pi_0(\mathscr{B})\) of the connected components of \(\mathscr{B}\), as
+  well as by \(\mathscr{B}^+\).
 \end{theorem}
 
 % TODO: Change this