  
  [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 4.8.2)[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
              0.9.6)[133X
  
  [33X[0;0YUsually   all   these  packages  should  come  with  a  sufficiently  recent
  GAP-installation  (4.8.3 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.[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;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
  
