  
  [1X1 [33X[0;0YIntroduction[133X[101X
  
  [33X[0;0YThis  package, [10XSL2Reps[110X, provides methods for constructing and testing matrix
  presentations  of  the  representations  of  [23X\mathrm{SL}_2(\mathbb{Z})[123X whose
  kernels are congruence subgroups of [23X\mathrm{SL}_2(\mathbb{Z})[123X.[133X
  
  [33X[0;0YIrreducible   representations   of   prime-power   level   are   constructed
  individually  by  using  the  Weil representations of quadratic modules, and
  from  these  a list of all representations of a given degree or level can be
  produced.  Each  representation is represented by a pair [23X(S,T)[123X, where [23XS[123X is a
  symmetric,  unitary  matrix and [23XT[123X is a diagonal matrix of finite order; this
  format is designed for the study of modular tensor categories in particular.[133X
  
  
  [1X1.1 [33X[0;0YInstallation[133X[101X
  
  [33X[0;0YTo       install       [10XSL2Reps[110X,       first       download      it      from
  [7Xhttps://snw-0.github.io/sl2-reps/[107X,  then place it in the [10Xpkg[110X subdirectory of
  your  GAP  installation  (or  in  the [10Xpkg[110X subdirectory of any other GAP root
  directory, for example one added with the [10X-l[110X argument).[133X
  
  [33X[0;0Y[10XSL2Reps[110X is then loaded with the GAP command[133X
  
  [33X[0;0Y[10Xgap> LoadPackage( "SL2Reps" );[110X[133X
  
  
  [1X1.2 [33X[0;0YUsage[133X[101X
  
  [33X[0;0YSpecific  irreducible  representations may be constructed via the methods in
  Chapter [14X3[114X, while lists of irreducible representations with a given degree or
  level may be constructed with those in Chapter [14X4[114X.[133X
  
  [33X[0;0YThis  package uses an [10XInfoClass[110X, [10XInfoSL2Reps[110X. It may be set to [10X0[110X (silent), [10X1[110X
  (info), or [10X2[110X (verbose). To change it, use[133X
  
  [33X[0;0Y[10Xgap> SetInfoLevel( InfoSL2Reps, k );[110X[133X
  
