Fix a lot of the broken links, especially outdated ones (#349)

_data/namelink.yml

@@ -3,10 +3,10 @@
 'Anton Betten': 'http://www.math.colostate.edu/~betten/'
 'Bettina Eick': 'http://www.icm.tu-bs.de/~beick/'
 'Charles Sims': 'http://www.math.rutgers.edu/~sims/'
-'Chris Jefferson': 'http://caj.host.cs.st-andrews.ac.uk/'
+'Chris Jefferson': 'http://heather.cafe/'
 'David Joyner': 'https://sites.google.com/site/wdjoyner/'
 'Derek Holt': 'http://www.maths.warwick.ac.uk/~dfh/'
-'Duane Broline': 'http://www.ux1.eiu.edu/~cfdmb/'
+'Duane Broline': 'https://web.archive.org/web/20100723193654/http://www.ux1.eiu.edu/~cfdmb/'
 "Eamonn O'Brien": 'http://www.math.auckland.ac.nz/~obrien'
 'Edmund Robertson': 'http://www-groups.dcs.st-and.ac.uk:80/~edmund/'
 'Frank Lübeck': 'http://www.math.rwth-aachen.de/~Frank.Luebeck/'
@@ -23,7 +23,7 @@
 'R. Wilson': 'http://for.mat.bham.ac.uk/R.A.Wilson/'
 'Russell Blyth': 'http://sylow.slu.edu/'
 'Stefan Kohl': 'https://stefan-kohl.github.io/'
-'Steve Linton': 'http://www.dcs.st-and.ac.uk/~sal'
+'Steve Linton': 'https://www.st-andrews.ac.uk/computer-science/people/sl4/'
 'Thomas Breuer': 'http://www.math.rwth-aachen.de/~Thomas.Breuer/'
 'Volkmar Felsch': 'http://www.math.rwth-aachen.de/~Volkmar.Felsch'
 'Werner Nickel': 'http://www.mathematik.tu-darmstadt.de/~nickel'

about/capabilities/algebras.md

@@ -38,7 +38,7 @@ extensions and to determine their automorphism groups.
 The package [QuaGroup](https://gap-packages.github.io/quagroup/) allows to 
 investigate quantum groups.
 
-On the home page of [Jan Draisma](https://mathsites.unibe.ch/jdraisma/) functions for working with the Weyl algebra and for the realisation of Lie algebras by means of derivations are found.
+On the home page of [Jan Draisma](https://web.archive.org/web/20240414220737/https://mathsites.unibe.ch/jdraisma/) functions for working with the Weyl algebra and for the realisation of Lie algebras by means of derivations are found.
 
 Four new packages for Lie algebras appeared in GAP 4.7 
 distribution:

about/capabilities/basic.md

@@ -56,8 +56,8 @@ GAP can compute with
   {%- include ref.html label="Matrices" text="matrices" %}, and
   {%- include ref.html label="Words" text="abstract words" %}.
 
-One can work with many algebracic structures. In addition to those listed under
-[Mathematical Capabilities]({{ site.baseurl }}/about/overview.html#mathematical-capabilities), there are e. g.
+One can work with many algebraic structures. In addition to those listed under
+[Mathematical Capabilities]({{ site.baseurl }}/capabilities/#mathematical-capabilities), there are e. g.
 
 - {% include ref.html label="Finite Fields" text="finite fields" %},
 - {% include ref.html label="Residue Class Rings" text="residue class rings" %} of integers (see also the package

about/capabilities/graphs.md

@@ -14,7 +14,7 @@ to construct graphs (with or without using  groups), to determine many
 invariants of graphs, to  classify complete subgraphs with various
 properties, to determine automorphism groups of graphs, and to test
 graph isomorphism (the  last two via an interface to B.D. McKay's
-[nauty](http://www.cs.sunysb.edu/~algorith/implement/nauty/implement.shtml) package).
+[nauty](https://www3.cs.stonybrook.edu/~algorith/implement/nauty/implement.shtml) package).
 A special feature of this package is the use of (subgroups of) the
 automorphism group of a graph (and hence of permutation group methods)
 to reduce the store required for many graphs and to reduce the time

about/capabilities/links.md

@@ -29,18 +29,14 @@ These include:
   mathematical objects encoded in 
   [OpenMath](http://www.openmath.org/), for the purpose of 
   exchanging them with other applications which are OpenMath enabled. 
-  (If the OpenMath site don't work, try the 
-  [unofficial mirror](http://openmath.activemath.org/).)
 
 -  A GAP package 
   [SCSCP](https://gap-packages.github.io/scscp) which implements the 
-  [Symbolic Computation Software Composability Protocol](http://www.symbolic-computing.org/scscp). 
+  [Symbolic Computation Software Composability Protocol](https://openmath.org/standard/scscp/). 
   Using it, GAP can communicate locally or remotely with any other 
   OpenMath-enabled SCSCP-compliant application which may be not only another computer algebra 
   system but also another instance of the GAP system or even, for example, an external 
   Java or C/C++ application that uses SCSCP API. 
-  See the [SCIEnce project homepage]( http://www.symbolic-computing.org/)
-  for the details about computer algebra systems and other sotware supporting SCSCP.
 
 - An interface
   [DISCRETA - GAP](http://www.mathe2.uni-bayreuth.de/discreta/GAP/discreta_gap.html) to the program 

about/index.md

@@ -27,7 +27,7 @@ packages provide links to other systems.
 
 
 ### GAP provides:
-- [Mathematical capabilities]({{ site.baseurl }}/capabilities/),
+- [Mathematical capabilities]({{ site.baseurl }}/capabilities/#mathematical-capabilities),
 - A {% include ref.html label="The Programming Language" text="programming language" %},
   also called GAP,
 - An {% include ref.html label="Main Loop and Break Loop" text="interactive environment" %}.

contacts/centres.md

@@ -29,7 +29,7 @@ have agreed to cooperate in this way:
 - [Braunschweig](https://www.tu-braunschweig.de/iaa/),
 - [Fort Collins](https://www.math.colostate.edu/~hulpke/CGT/CGT.html),
 - [Kaiserslautern](https://math.rptu.de/ags/agag/), and
-- [St Andrews](https://www-circa.mcs.st-and.ac.uk/).
+- [St Andrews](https://circa.st-andrews.ac.uk/).
 
 This list may change, if new Centres emerge, or existing ones withdraw.
 

doc/bib/index.md

@@ -73,7 +73,7 @@ database.
   codes in the appropriate categories. 
   Click on the name of the category to see the list of papers in this category.
   We acknowledge the [American Mathematical Society](https://www.ams.org/) 
-  for the opportunity to use the [MathSciNet](httpss://www.ams.org/mathscinet/) 
+  for the opportunity to use the [MathSciNet](https://www.ams.org/mathscinet/) 
   database for performing this analysis.
 
   <table>

doc/learn/index.md

@@ -84,12 +84,6 @@ parent: Documentation
     <br />&nbsp;
   </li> 
 -->
-- [Uma&nbsp;Introducao&nbsp;ao&nbsp;GAP](http://www.fc.up.pt/cmup/monograph/gap-notas.pdf)
-    An introduction to GAP (in Portuguese) by 
-    [Manuel&nbsp;Delgado](http://www.fc.up.pt/cmup/mdelgado),
-    University of Porto.
-    An introduction to using GAP to study automata 
-    and semigroups.
 - {% include namelink.html name="Olexandr Konovalov" %} has
     written an explanation how to create new objects in GAP using the example
     of [circle multiplication](http://www.cs.st-andrews.ac.uk/~alexk/circle/chap2.html).

doc/teach/index.md

@@ -41,15 +41,14 @@ parent: Documentation
     by Akihito Kikuchi (Springer, 2018) uses GAP to explain how to use computer algebra for applications in
     solid-state simulation.
   - ["Computer Algebra"](http://lib.brsu.by/sites/default/files/books/%D0%9A%D0%BE%D0%BC%D0%BF%D1%8C%D1%8E%D1%82%D0%B5%D1%80%D0%BD%D0%B0%D1%8F%20%D0%B0%D0%BB%D0%B3%D0%B5%D0%B1%D1%80%D0%B0_2.pdf) - teaching material in Russian by D. V. Gritsuk and A. A. Trofimuk (Brest State A. S. Pushkin University, Belarus, 2018).
-  - M. D'Anna, V. Micale and [$2]($1) gave the course
-    ["Semigruppi numerici e applicazioni"](http://www.scuolasuperiorecatania.it/it/semigruppi-numerici-e-applicazioni-0)
-    at the Scuola Superiore di Catania, during the academic year 2016-17, 
+  - M. D'Anna, V. Micale and [P. A. García Sánchez](https://www.ugr.es/~pedro) gave the course
+    "Semigruppi numerici e applicazioni" at the Scuola Superiore di Catania, during the academic year 2016-17, 
     where GAP was used. They gave an introduction to NumericalSgps and GUAVA packages.
     [This repository](https://github.com/pedritomelenas/SSC-Semigroups) contains a 
     [live tutorial of NumericalSgps](https://pedritomelenas.github.io/SSC-Semigroups/Live/gap-numericalsgps-thebelab.html)
     using [Thebe](https://github.com/executablebooks/thebe).
   - The book ["Numerical Semigroups and Applications"](https://www.springer.com/gp/book/9783319823256)
-    by Abdallah Assi and [$2]($1) (Springer, 2016) contains
+    by Abdallah Assi and [Pedro A. García Sánchez](https://www.ugr.es/~pedro) (Springer, 2016) contains
     many examples and tutorials with the NumericalsSps GAP package.
   - Teaching material in Spanish by Leandro Vendramin:
     - [Una introducción al álgebra con GAP](http://mate.dm.uba.ar/~lvendram/lectures/GAP.pdf) (2016).
@@ -66,7 +65,7 @@ parent: Documentation
     [Abstract Algebra in GAP](https://www.math.colostate.edu/%7Ehulpke/CGT/howtogap.pdf) (2011)
     by {% include namelink.html name="Alexander Hulpke" %},
     with contributions by Kenneth Monks and Ellen Ziliak.
-  - The book ["Representations of Groups: A Computational Approach"](https://www.cambridge.org/vi/academic/subjects/mathematics/algebra/representations-groups-computational-approach)
+  - The book ["Representations of Groups: A Computational Approach"](https://www.cambridge.org/vi/universitypress/subjects/mathematics/algebra/representations-groups-computational-approach)
     by Klaus Lux and Herbert Pahlings (Cambridge University Press, 2010) provides a number of computational exercises and examples using GAP.
   - The book ["Numerical Semigroups"](https://link.springer.com/book/10.1007/978-1-4419-0160-6)
     by J. C. Rosales and [P. A. García Sánchez](https://www.ugr.es/~pedro) (Springer, 2009).
@@ -86,7 +85,7 @@ parent: Documentation
     in June 2004 under the auspices of the Mathematical Association of
     America's Professional Enhancement Program.
   - A course
-    [Mathematics 3530](http://www.ux1.eiu.edu/~cfdmb/gap/index.html) - Abstract Algebra,
+    [Mathematics 3530](https://web.archive.org/web/20100728031334/http://www.ux1.eiu.edu/~cfdmb/gap/index.html) - Abstract Algebra,
     given in Fall 2003 at
     [ Eastern Illinios University](http://www.eiu.edu/)
     by {% include namelink.html name="Duane Broline" %}.
@@ -133,7 +132,7 @@ parent: Documentation
     [ITC manual]({{ site.docsurl }}/pkg/itc/htm/chapters.htm).
 
 Other examples of use of GAP in teaching include: 
-- [Material, in Portugese, for a Mini-Course about GAP](http://pet.mat.unb.br/pub/Minicurso_de_GAP.pdf),
+- [Material, in Portugese, for a Mini-Course about GAP](https://web.archive.org/web/20230204205117/http://pet.mat.unb.br/pub/Minicurso_de_GAP.pdf),
 by Ayrton Anjos Teixeira from 2022
 - [GAP exercises](https://github.com/MWhybrow92/Permutation-Groups) for the
 Theory of permutation groups course by [Madeleine Whybrow](https://madeleinewhybrow.wordpress.com/)
@@ -161,14 +160,14 @@ since 2016.
 "Análisis y diseño de algoritmos" (Analysis and Design of Algorithms),
 student research projects and doctoral studies since 2014.
 - Uygulamalı Cebir (Applied Algebra), Sembolik Hesaplama (Symbolic Computation)
-and GAP Programlama (GAP Programming) by [$2]($1) (Osmangazi University, Turkey),
+and GAP Programlama (GAP Programming) by [Alper Odabaş](http://fef.ogu.edu.tr/aodabas/) (Osmangazi University, Turkey),
 starting from 2013.
-- Use of GAP at the Universidad de Almería (Spain) in the course Software en Matemáticas (since 2018);
+<!-- - Use of GAP at the Universidad de Almería (Spain) in the course Software en Matemáticas (since 2018);
 and also the GUAVA package for Coding Theory in the course
 ["Teoría de la Información y la Codificación"](http://cms.ual.es/UAL/ht/estudios/titulaciones/titulacion/asignaturas/asignatura/TITULACION4100?id=&idTit=4100&idAss=40007321&idCaracter=O)
 in the degree of Computer Science (since 2012). GAP was also used in the course
 ["Ampliación de Matemática Discreta"](http://cms.ual.es/UAL/universidad/departamentos/matematicas/docencia/asignaturas/asignatura/index.htm?id=6250&idTit=4000&idAss=40002202&idCaracter=B)
-during several years, mainly for polynomials over finite extensions of finite fields, between 2004 and 2011.
+during several years, mainly for polynomials over finite extensions of finite fields, between 2004 and 2011. -->
 - Grupos y Anillos (Groups and Rings), Códigos Correctores y Criptografía (Error Correcting Codes and Cryptography), Teoría de Números (Number Theory)
 by [Ángel del Río](https://www.um.es/adelrio/) (Universidad de Murcia, Spain), starting circa 2010.
 - Number Theory and Applications; Semigroups, Automata and Languages (the package Automata);

index.md

@@ -5,6 +5,7 @@ nav_order: 1
 nav_exclude: true
 ---
 
+
 <h1 style="text-align:center;">GAP - Groups, Algorithms, Programming</h1>
 
 <h2 style="text-align:center;">A System for Computational Discrete Algebra</h2>
@@ -18,14 +19,15 @@ text="programming language" %}, a library of thousands of functions
 implementing algebraic algorithms written in the GAP language as well as
 large data libraries of
 algebraic objects. See
-[here]({{ site.baseurl }}/about/overview.html) for details of the mathematical capabilities.
+[here]({{ site.baseurl }}capabilities/) for details of the mathematical capabilities.
 The system, including source, is distributed
 [freely]({{ site.baseurl }}/copyright/).
 You can study and easily modify or extend it for your special use.
 
 
 ### How to obtain GAP?
 
+
 The current version is
 [GAP {{site.data.release.version}}]({{ site.baseurl }}/install/) released on {{site.data.release.date}}
 and it can be obtained from our [install page]({{ site.baseurl }}/install/).
@@ -43,10 +45,10 @@ If you have any questions, or suggestions for GAP, the repository, or
 documentation, feel free to contact us via the [open GAP development
 mailing list](https://lists.uni-kl.de/gap/info/gap) or
 submit an issue or a pull request on GitHub.
-There is an [extensive documentation](Doc/doc.html) advising how to
+There is an [extensive documentation]({{ site.baseurl }}/doc/) advising how to
 write a GAP code. Also there is a
 [guidance](https://gap-packages.github.io/example/) on
-developing a [GAP package](packages) and its
+developing a [GAP package]({{ site.baseurl }}/packages/) and its
 [submission]({{ site.baseurl }}/packages/authors/submit.html) to GAP.
 
 
@@ -61,12 +63,12 @@ Mathematik](https://www.math.rwth-aachen.de/LDFM/), RWTH Aachen in
 [1986]({{ site.baseurl }}/about/history/preface_2.4.html).
 After 1997
 the development of GAP was coordinated in [St
-Andrews](https://www-circa.mcs.st-and.ac.uk/). Since March 2005, the
+Andrews](https://circa.st-andrews.ac.uk/). Since March 2005, the
 [GAP Centers]({{ site.baseurl }}/centres/) in
 [Aachen](https://www.math.rwth-aachen.de/LDFM/),
 [Braunschweig](https://www.tu-braunschweig.de/iaa/),
 Fort Collins,
-and [St Andrews](https://www-circa.mcs.st-and.ac.uk/) took over coordination.
+and [St Andrews](https://circa.st-andrews.ac.uk/) took over coordination.
 They were joined by [Kaiserslautern](https://math.rptu.de/ags/agag/)
 as fifth GAP center in 2020.
 Since July 2022, the GAP center in Kaiserslautern is coordinating the

packages/authors/authors.md

@@ -188,7 +188,7 @@ updates as follows:
 - We advise package authors to maintain an update "history",
   which documents the changes from one version to another.
   A good example is contained in the
-  [README]({{ site.docsurl }}/pkg/design/README.design)
+  [README](https://github.com/gap-packages/grape/blob/master/CHANGES.md)
   file of the DESIGN package of Leonard Soicher.
 
 

packages/index.md

@@ -30,5 +30,5 @@ Note that newer versions might be available on the package websites.
 |   | Name | Version | Date | | Subtitle |
 {: id="packageList" class="display"}
 
-The table above is generated using the open source software [Datatables](https://datatables.net/" target="_blank).
+The table above is generated using the open source software [Datatables](https://datatables.net/).