  
  [1X6 [33X[0;0YRemarks on technical problems and the implementation[133X[101X
  
  
  [1X6.1 [33X[0;0YMaking the HeLP-package run[133X[101X
  
  [33X[0;0YFor  all  basic  functionalities  of the HeLP-package (using only the solver
  normaliz)  the  standard  GAP-installation should suffice to make everything
  work:     Get     the    most    recent    GAP    from    the    GAP-webpage
  ([7Xhttps://www.gap-system.org/[107X)   by   following   the   instructions  on  the
  Download-page.  Make  sure  to also install all packages needed to run HeLP.
  Then just start GAP and type [9XLoadPackage("HeLP");[109X.[133X
  
  [33X[0;0YHere  is  a  checklist  what to do, if the package does not work or you also
  want to use the solver 4ti2:[133X
  
  [30X    [33X[0;6YMake  sure  you  have  sufficiently  new  versions  of  the  following
        software:[133X
  
        [30X    [33X[0;12YGAP ([7Xhttps://www.gap-system.org/[107X) (at least 4.13)[133X
  
        [30X    [33X[0;12Ythe                      GAP-package                     CTblLib
              ([7Xhttps://www.math.rwth-aachen.de/~Thomas.Breuer/ctbllib/[107X)    (at
              least 1.2.2)[133X
  
        [30X    [33X[0;12Ythe   GAP-package  IO  ([7Xhttps://gap-packages.github.io/io/[107X)  (at
              least  4.2;  see  also the next bullet point if this package can
              not be loaded)[133X
  
        [30X    [33X[0;12Ythe                   GAP-package                  4ti2Interface
              ([7Xhttps://homalg-project.github.io/pkg/4ti2Interface/[107X)  (at least
              2015.04.29; this package needs the IO-package)[133X
  
        [30X    [33X[0;12Ythe                 GAP-package                NormalizInterface
              ([7Xhttps://gap-packages.github.io/NormalizInterface//[107X)  (at  least
              1.4.1)[133X
  
  [33X[0;0YUsually   all   these  packages  should  come  with  a  sufficiently  recent
  GAP-installation  (4.13  or newer) and should be contained in the pkg-folder
  of  the  GAP-installation.  To  see if they are working you can load them by
  typing  [9XLoadPackage("[name]");[109X  after starting GAP, where [9X[name][109X is the name
  of the package. The IO and CTblLib are strictly necessary for the package to
  load.  4ti2  and/or  normaliz  are  needed  for full functionality, but some
  useful functions also work without them.[133X
  
  [30X    [33X[0;6YThe  IO-package  needs  a  C-part  to  be compiled. To see if this has
        already  been  done  on  your system, you can enter [9XLoadPackage("IO");[109X
        after starting GAP. If the result is [9Xfail[109X and the package is contained
        in  the  pkg-folder,  than most likely the C-part is not yet compiled.
        For  information  on  installation and in particular on how to compile
        the            C-part,            see            the            manual
        ([7Xhttps://gap-packages.github.io/io/doc/chap0.html[107X)    (in   particular
        Chapter 2) or the README-file of that package.[133X
  
  [30X    [33X[0;6YThe   installation   of  normaliz  is  possible  via  the  GAP-package
        NormalizInterface ([7Xhttps://gap-packages.github.io/NormalizInterface//[107X)
        (at  least  0.9.6).  Just  access  the  folder  in  a  terminal and do
        [9X./build-normaliz.sh; ./configure; make[109X.[133X
  
  [30X    [33X[0;6YIf  you  want  to  use  4ti2,  please  make  sure  that 4ti2.github.io
        ([7Xhttps://4ti2.github.io[107X)   (Version   1.6.5   or  newer)  is  properly
        installed.  In  case  of  an  error-message  "The  executable 'zsolve'
        provided   by   the   software  4ti2  was  not  found."  after  typing
        [9XLoadPackage("HeLP");[109X  either the software is not properly installed or
        installed  in  a directory where GAP can not find it, i.e. a directory
        not  contained  in the path-variable. The content of this variable can
        typically  be  displayed by typing [9Xecho $PATH[109X (Linux, Mac) [9Xecho %PATH%[109X
        (Windows)  in  a  terminal  or  a  command  prompt. The manual of 4ti2
        contains  several  pages of information on how to install the program.
        Note  that  the  installation  of  4ti2  requires  gcc  (g++)  and gmp
        installed  (which  come  with  many  Linux  installations  or  can  be
        installed  using  a  package  manager).  Make sure to execute all four
        commands   indicated   in   the  4ti2  manual  (possibly  without  the
        [9X--prefix=[109X-part):[133X
  
        [33X[0;6Y[9X./configure --prefix=INSTALLATION-DIRECTORY[109X[133X
  
        [33X[0;6Y[9Xmake[109X[133X
  
        [33X[0;6Y[9Xmake check[109X[133X
  
        [33X[0;6Y[9Xmake install-exec[109X[133X
  
        [33X[0;6YDepending  on  the  settings  of  your  system  you  might  need  root
        privileges  (type  [9Xsudo[109X in front of every command) to unpack the files
        and  install  them.  To check whether the installation worked, you can
        enter  [9Xzsolve[109X in a terminal. In case one of the required programs (g++
        or  gmp)  was  not installed when running [9Xmake[109X for the first time, you
        might  need  to run [9Xmake clean[109X and the above commands afterwards again
        (several times) to compile 4ti2 successfully. If you already have 4ti2
        installed  in  a directory not contained in the path-variable and want
        to avoid a re-installation, in many cases the following helps:[133X
  
        [30X    [33X[0;12YStart  a  terminal  and  access  a  path written in your bash or
              system_bash. Typically [9Xusr/local/bin[109X should work.[133X
  
        [30X    [33X[0;12YRun  [9Xln  -s  /[PathToZsolve] zsolve[109X, where [9X[PathToZsolve][109X is the
              path  to the executable zsolve. This sets a symlink to the right
              place.  E.g.  [9Xln  -s /opt/4ti2/bin/zsolve zsolve[109X was used on the
              (Linux) computers in Stuttgart.[133X
  
  [30X    [33X[0;6YIn   case   you   use  4ti2,  we  also  recommend  to  install  lrslib
        ([7Xhttps://cgm.cs.mcgill.ca/~avis/C/lrs.html[107X),  at  least  version  4.3.
        This  software provides the 'redund' command, which can be switched on
        and off within HeLP, but which often leads to better performances (cf.
        [2XHeLP_UseRedund[102X  ([14X3.5-2[114X)). For installation see the User's Guide or the
        Readme-file  on the above mentioned homepage. Usually, after unpacking
        in  a  directory contained in the path-variable it should be enough to
        call[133X
  
        [33X[0;6Y[9Xmake all[109X[133X
  
        [33X[0;6Y(possibly as root) inside the lrslib-directory.[133X
  
  [30X    [33X[0;6YIf  this  does  not  help  to  get HeLP running, please feel more than
        welcome to contact one of the maintainers of the package.[133X
  
  
  [1X6.2 [33X[0;0YRunning the package without 4ti2 and normaliz[133X[101X
  
  [33X[0;0YEven  if none of the solvers is installed and even when none of the packages
  4ti2Interface   and   NormalizInterface   can  be  loaded,  some  restricted
  functionality  is  still  available.  For  instance  one  can define partial
  augmentations  manually  and  verify,  if  it satisfies the HeLP constraints
  using  [2XHeLP_VerifySolution[102X  ([14X3.6-1[114X),  obtain  the  corresponding eigenvalues
  under  representations  using  [2XHeLP_MultiplicitiesOfEigenvalues[102X  ([14X3.10-1[114X) or
  apply the Wagner test to them using [2XHeLP_WagnerTest[102X ([14X3.7-1[114X).[133X
  
  
  [1X6.3 [33X[0;0YHow much 4ti2 and normaliz is really there?[133X[101X
  
  [33X[0;0YThe  reason, why the programs 4ti2 and normaliz are used in this package, is
  basically that they can solve systems of linear inequalities efficiently and
  there  exist good GAP-Interfaces for them. However there is only one line of
  code  where  a  function  is  called  which accesses 4ti2 and a few more for
  normaliz.  Thus  the effort of using another solver of inequalities would be
  not  so  big, if there is a GAP-Interface for it. If you are aware of such a
  solver  and would like to use it in this package, please contact the authors
  of this package. We will be happy to help.[133X
  
