   ;; \omicron \Omicron
   ;; \pi \Pi
   ("Gr"  . ("ρ"))  ("GR"  . ("Ρ"))
-  ("Gs"  . ("σ"))  ("GS"  . ("Σ"))
+  ("Gs"  . ("σ"))  ("GS"  . ("Σ")) ("S"  . ("Σ"))
   ("Gt"  . ("τ"))  ("GT"  . ("Τ"))
   ("Gu"  . ("υ"))  ("GU"  . ("Υ"))
   ("Gf"  . ("φ"))  ("GF"  . ("Φ"))


  ;; Big/small, black/white.

  ("t" . ,(lean-input-to-string-list "▸▹►▻◂◃◄◅▴▵▾▿◢◿◣◺◤◸◥◹"))
  ("Tr" . ,(lean-input-to-string-list "◀◁▶▷▲△▼▽◬◭◮"))
  ("transport" . ("▹"))

  ("tb" . ,(lean-input-to-string-list "◂▸▴▾◄►◢◣◤◥"))
  ("tw" . ,(lean-input-to-string-list "◃▹▵▿◅▻◿◺◸◹"))


  ;; Inequality and similar symbols.

  ("leq"  . ,(lean-input-to-string-list "≤≦≲<≪⋘ ≶≺≼≾⊂⊆ ⋐⊏⊑ ⊰⊲⊴⋖⋚⋜⋞"))
  ("leqn" . ,(lean-input-to-string-list "≰≨≮≴⋦   ≸⊀ ⋨⊄⊈⊊  ⋢⋤ ⋪⋬   ⋠"))
  ("geq"  . ,(lean-input-to-string-list "≥≧≳>≫⋙ ≷≻≽≿⊃⊇ ⋑⊐⊒ ⊱⊳⊵⋗⋛⋝⋟"))
  ("geqn" . ,(lean-input-to-string-list "≱≩≯≵⋧ ≹  ⊁ ⋩⊅⊉⊋  ⋣⋥ ⋫⋭   ⋡"))

  ("<="   . ("≤"))  (">="   . ("≥"))
  ("<=n"  . ("≰"))  (">=n"  . ("≱"))
