diff --git a/.github/actions/test_with_valgrind/action.yml b/.github/actions/test_with_valgrind/action.yml
new file mode 100644
index 000000000..f15544ea1
--- /dev/null
+++ b/.github/actions/test_with_valgrind/action.yml
@@ -0,0 +1,88 @@
+name: Run package tests
+description: Run package tests
+inputs:
+  NO_COVERAGE:
+    description: set to a non-empty string to suppress gathering coverage
+    required: false
+    type: string
+    default: ""
+  GAP_TESTFILE:
+    description: Name of the GAP file to be read for executing the package tests (overrides TestFile in PackageInfo.g)
+    required: false
+    type: string
+    default: ""
+  only-needed:
+    description: If set to true then only needed dependencies of the package being tested are loaded
+    required: false
+    type: boolean
+    default: false
+  pre-gap:
+    description: Commands to be prepended to gap
+    required: false
+    type: string
+    default: ""
+
+env:
+  CHERE_INVOKING: 1
+
+runs:
+  using: composite
+  steps:
+    - name: Run tests
+      run: |
+        set -ex
+
+        GAPROOT=${GAPROOT-$HOME/gap}
+
+        # set up a custom GAP root containing only this package, so that
+        # we can force GAP to load the correct version of this package
+        # (we already did that in build_pkg.sh, but we do it again here,
+        # to allow the occasional instance where a package wants to also
+        # run the tests of others packages, by invoking this script multiple
+        # times in different directories)
+        mkdir -p /tmp/gaproot/pkg/
+        ln -f -s $PWD /tmp/gaproot/pkg/
+
+        # start GAP with custom GAP root, to ensure correct package version is loaded
+        GAP="${{ inputs.pre-gap }} $GAPROOT/gap -l /tmp/gaproot; --quitonbreak"
+
+        if ${{ inputs.only-needed }} = 'true' ; then
+          GAP="$GAP -A"
+        fi
+
+        # Unless explicitly turned off by setting the NO_COVERAGE environment variable,
+        # we collect coverage data
+        if [[ -z "${{ inputs.NO_COVERAGE }}" ]]; then
+            mkdir -p ${COVDIR-coverage}
+            GAP="$GAP --cover ${COVDIR-coverage}/$(mktemp XXXXXX).coverage"
+        fi
+
+        cat > __TEST_RUNNNER__.g <<EOF
+
+        GAP_TESTFILE:="${{ inputs.GAP_TESTFILE }}";
+        Read("PackageInfo.g");
+        info := GAPInfo.PackageInfoCurrent;
+        if IsEmpty(GAP_TESTFILE) or not IsExistingFile(GAP_TESTFILE) then
+            GAP_TESTFILE := info.TestFile;
+        fi;
+        # Load the package with debug info
+        SetInfoLevel(InfoPackageLoading, PACKAGE_DEBUG);
+        SetPackagePath(info.PackageName, "/tmp/gaproot/pkg/$(basename $PWD)");
+        if ${{ inputs.only-needed }} = true then
+           LoadPackage(info.PackageName : OnlyNeeded);
+        else
+           LoadPackage(info.PackageName);
+        fi;
+        SetInfoLevel(InfoPackageLoading, PACKAGE_ERROR);
+        Print("Now running tests from ", GAP_TESTFILE, "\n");
+        if EndsWith(GAP_TESTFILE, ".tst") then
+            QUIT_GAP(Test(GAP_TESTFILE, rec(compareFunction := "uptowhitespace")));
+        else
+            Read(GAP_TESTFILE);
+            Error("Package TestFile did not exit gap");
+        fi;
+        EOF
+
+        $GAP __TEST_RUNNNER__.g
+
+      shell: bash
diff --git a/.github/workflows/codespell.yml b/.github/workflows/codespell.yml
index 6e85488bf..3e93fec51 100644
--- a/.github/workflows/codespell.yml
+++ b/.github/workflows/codespell.yml
@@ -1,4 +1,4 @@
-name: codespell
+name: Codespell
 on:
   workflow_dispatch:
   pull_request:
@@ -10,5 +10,5 @@ jobs:
   codespell:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: codespell-project/actions-codespell@v2
+      - uses: actions/checkout@v4
+      - uses: codespell-project/actions-codespell@v2
diff --git a/.github/workflows/config_options.yml b/.github/workflows/config_options.yml
new file mode 100644
index 000000000..1485ce1b2
--- /dev/null
+++ b/.github/workflows/config_options.yml
@@ -0,0 +1,100 @@
+name: Config-options
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
+      - stable-*.*
+  schedule:
+    # Every day at 3:30 AM UTC
+    - cron: 30 3 * * *
+env:
+  NO_COVERAGE: true
+
+jobs:
+  with-external-planarity-bliss:
+    name: ${{ matrix.bliss }} ${{ matrix.planarity }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        planarity:
+          - --with-external-planarity
+          - ""
+        bliss:
+          - --with-external-bliss
+          - ""
+        exclude:
+          - planarity: ""
+            bliss: ""
+    defaults:
+      run:
+        shell: bash -l {0}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Output g++ version . . .
+        run: g++ --version
+      - name: Install micromamba environment from environment.yml . . .
+        uses: mamba-org/setup-micromamba@v1
+        with:
+          environment-name: digraphs
+          cache-environment: true
+          create-args: ${{ matrix.bliss && 'bliss' || '' }} ${{ matrix.planarity && 'planarity' || ''}}
+      - name: Set environment variables . . .
+        run: |
+          echo "PKG_CONFIG_PATH=$MAMBA_ROOT_PREFIX/envs/digraphs/lib/pkgconfig:$MAMBA_ROOT_PREFIX/envs/digraphs/share/pkgconfig" >> $GITHUB_ENV
+          echo "LD_LIBRARY_PATH=$MAMBA_ROOT_PREFIX/envs/digraphs/lib" >> $GITHUB_ENV
+          echo "CFLAGS=-I$MAMBA_ROOT_PREFIX/envs/digraphs/include" >> $GITHUB_ENV
+          echo "LDFLAGS=-L$MAMBA_ROOT_PREFIX/envs/digraphs/lib" >> $GITHUB_ENV
+      - name: Install GAP and clone/compile necessary packages . . .
+        uses: gap-actions/setup-gap@v2
+        with:
+          GAP_PKGS_TO_CLONE: NautyTracesInterface digraphs/graphviz
+          GAP_PKGS_TO_BUILD: io orb datastructures grape NautyTracesInterface
+          GAPBRANCH: stable-4.13
+      - name: Build Digraphs . . .
+        uses: gap-actions/build-pkg@v1
+        with:
+          CONFIGFLAGS: ${{ matrix.bliss }} ${{ matrix.planarity }}
+      - name: Run Digraphs package's tst/teststandard.g . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+
+  all-options:
+    name: ${{ matrix.debug }} ${{ matrix.warnings }} ${{ matrix.without-intrinsics }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        warnings:
+          - "--enable-compile-warnings"
+          - ""
+        debug:
+          - "--enable-debug"
+          - ""
+        without-intrinsics:
+          - "--without-intrinsics"
+          - ""
+        exclude:
+          - warnings: ""
+            debug: ""
+            without-intrinsics: ""
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Output g++ version . . .
+        run: g++ --version
+      - name: Install GAP and clone/compile necessary packages . . .
+        uses: gap-actions/setup-gap@v2
+        with:
+          GAP_PKGS_TO_CLONE: NautyTracesInterface digraphs/graphviz
+          GAP_PKGS_TO_BUILD: io orb datastructures grape NautyTracesInterface
+          GAPBRANCH: stable-4.13
+      - name: Build Digraphs . . .
+        uses: gap-actions/build-pkg@v1
+        with:
+          CONFIGFLAGS: ${{ matrix.debug }} ${{ matrix.without-intrinsics }} ${{ matrix.warnings && '--enable-compile-warnings WARNING_CXXFLAGS="-Werror" WARNING_CFLAGS="-Werror"' || '' }}
+      - name: Run Digraphs package's tst/teststandard.g . . .
+        uses: gap-actions/run-pkg-tests@v2
diff --git a/.github/workflows/gap.yml b/.github/workflows/gap.yml
deleted file mode 100644
index 4e1bc5913..000000000
--- a/.github/workflows/gap.yml
+++ /dev/null
@@ -1,143 +0,0 @@
-name: "GAP"
-on:
-  workflow_dispatch:
-  pull_request:
-  push:
-    branches:
-      - main
-      - stable-*.*
-  schedule:
-    # Every day at 3:30 AM UTC
-    - cron: '30 3 * * *'
-
-env:
-  DIGRAPHS_LIB: digraphs-lib-0.6
-
-jobs:
-  test-unix:
-    name: "${{ matrix.os }}${{ matrix.ABI }} / GAP ${{ matrix.gap-branch }}"
-    runs-on: "${{ matrix.os }}-latest"
-    strategy:
-      fail-fast: false
-      matrix:
-        os:
-          - ubuntu
-        gap-branch:
-          - master
-          - stable-4.11
-          - stable-4.12
-          - stable-4.13
-        pkgs-to-clone:
-          - NautyTracesInterface
-        ABI: ['']
-
-        include:
-          - gap-branch: stable-4.10
-            os: ubuntu
-          - gap-branch: master
-            pkgs-to-clone: "NautyTracesInterface"
-            os: macos
-          - gap-branch: master
-            os: ubuntu
-            ABI: 32
-
-    steps:
-      - uses: actions/checkout@v4
-      - name: "Install dependencies"
-        if: ${{ runner.os == 'macOS' }}
-        run: brew install automake
-      - name: "Install GAP and clone/compile necessary packages"
-        uses: gap-actions/setup-gap@v2
-        with:
-          GAP_PKGS_TO_CLONE: "${{ matrix.pkgs-to-clone }}"
-          GAP_PKGS_TO_BUILD: "io orb profiling grape NautyTracesInterface datastructures"
-          GAPBRANCH: ${{ matrix.gap-branch }}
-          ABI: ${{ matrix.ABI }}
-      - name: "Build Digraphs"
-        uses: gap-actions/build-pkg@v1
-        with:
-          ABI: ${{ matrix.ABI }}
-      - name: "Install digraphs-lib"
-        run: |
-          curl --retry 5 -L -O "https://digraphs.github.io/Digraphs/${{ env.DIGRAPHS_LIB }}.tar.gz"
-          tar xf "${{ env.DIGRAPHS_LIB }}.tar.gz"
-      - name: "Clone datastructures v0.3.0"
-        if: ${{ matrix.gap-branch == 'stable-4.10' }}
-        run: |
-            rm -rf $HOME/gap/pkg/datastructures
-            cd $HOME/gap/pkg/
-            git clone https://github.com/gap-packages/datastructures.git datastructures
-            cd datastructures
-            git checkout v0.3.0
-            ./configure
-            make
-      - name: "Run DigraphsTestInstall"
-        uses: gap-actions/run-pkg-tests@v2
-        with:
-          GAP_TESTFILE: "tst/github_actions/install.g"
-      - name: "Run DigraphsTestStandard"
-        uses: gap-actions/run-pkg-tests@v2
-        with:
-          GAP_TESTFILE: "tst/github_actions/standard.g"
-      - name: "Run DigraphsTestManualExamples"
-        uses: gap-actions/run-pkg-tests@v2
-        with:
-          GAP_TESTFILE: "tst/github_actions/examples.g"
-      - name: "Run DigraphsTestExtreme"
-        uses: gap-actions/run-pkg-tests@v2
-        with:
-          GAP_TESTFILE: "tst/github_actions/extreme.g"
-      - uses: gap-actions/process-coverage@v2
-      - uses: codecov/codecov-action@v3
-
-  test-cygwin:
-    name: "cygwin / GAP master"
-    runs-on: windows-2019
-    env:
-      CHERE_INVOKING: 1
-    steps:
-      - uses: actions/checkout@v4
-      - uses: gap-actions/setup-cygwin@v1
-      - uses: gap-actions/setup-gap@cygwin-v2
-        with:
-          GAP_PKGS_TO_BUILD: "io orb profiling grape datastructures"
-      - uses: gap-actions/build-pkg@cygwin-v1
-      - name: "Install digraphs-lib"
-        run: |
-          curl --retry 5 -L -O "https://digraphs.github.io/Digraphs/${{ env.DIGRAPHS_LIB }}.tar.gz"
-          tar xf "${{ env.DIGRAPHS_LIB }}.tar.gz"
-      - uses: gap-actions/run-pkg-tests@cygwin-v2
-      - uses: gap-actions/process-coverage@cygwin-v2
-      - uses: codecov/codecov-action@v3
-
-  with-external-planarity-bliss:
-    runs-on: "ubuntu-latest"
-    env:
-      GAPBRANCH: "stable-4.12"
-      ABI: 64
-      PKG_CONFIG_PATH: "/home/runner/micromamba/envs/digraphs/lib/pkgconfig:/home/runner/micromamba/envs/digraphs/share/pkgconfig/"
-      LD_LIBRARY_PATH: "/home/runner/micromamba/envs/digraphs/lib"
-      CFLAGS: "-I/home/runner/micromamba/envs/digraphs/include"
-      LDFLAGS: "-L/home/runner/micromamba/envs/digraphs/lib"
-    defaults:
-      run:
-        shell: bash -l {0}
-    steps:
-      - uses: actions/checkout@v4
-      - name: "Install micromamba environment from environment.yml . . ."
-        uses: mamba-org/setup-micromamba@v1
-        with:
-            environment-file: environment.yml
-            cache-environment: true
-      - name: "Activate \"digraphs\" environment . . ."
-        run:  micromamba activate digraphs
-      - name: "Install GAP and clone/compile necessary packages"
-        uses: gap-actions/setup-gap@v2
-        with:
-          GAP_PKGS_TO_BUILD: "io orb profiling grape datastructures"
-      - name: "Build Digraphs"
-        uses: gap-actions/build-pkg@v1
-        with:
-          CONFIGFLAGS: --with-external-planarity --with-external-bliss
-      - name: "Run Digraphs package's tst/teststandard.g"
-        uses: gap-actions/run-pkg-tests@v2
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index bc660dc44..4c3121a91 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -1,4 +1,4 @@
-name: "Lint"
+name: Lint
 on:
   workflow_dispatch:
   pull_request:
@@ -8,11 +8,11 @@ on:
       - stable-*.*
   schedule:
     # Every day at 3:30 AM UTC
-    - cron: '30 3 * * *'
+    - cron: 30 3 * * *
 
 jobs:
   lint:
-    name: "${{ matrix.linter }}"
+    name: ${{ matrix.linter }}
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -21,12 +21,11 @@ jobs:
           - gaplint
           - cpplint
     steps:
-    - name: "Check out the repository"
-      uses: actions/checkout@v4
-    - name: "Set up Python"
-      uses: actions/setup-python@v5
-    - name: "Install ${{ matrix.linter }} with pip"
-      run: pip install ${{ matrix.linter }}
-    - name: "Run ${{ matrix.linter }} on the Digraphs package"
-      run: bash etc/${{ matrix.linter }}.sh
-
+      - name: Check out the repository . . .
+        uses: actions/checkout@v4
+      - name: Set up Python . . .
+        uses: actions/setup-python@v5
+      - name: Install ${{ matrix.linter }} with pip . . .
+        run: pip install ${{ matrix.linter }}
+      - name: Run ${{ matrix.linter }} on the Digraphs package . . .
+        run: bash etc/${{ matrix.linter }}.sh
diff --git a/.github/workflows/manual.yml b/.github/workflows/manual.yml
index 4f4b44917..19690801a 100644
--- a/.github/workflows/manual.yml
+++ b/.github/workflows/manual.yml
@@ -1,4 +1,4 @@
-name: "Manual"
+name: Manual
 on:
   workflow_dispatch:
   pull_request:
@@ -8,15 +8,15 @@ on:
       - stable-*.*
   schedule:
     # Every day at 3:20 AM UTC
-    - cron: '20 3 * * *'
+    - cron: "20 3 * * *"
 
 jobs:
   manual:
-    name: "compile and upload manual"
+    name: compile and upload manual
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: "Install TeX Live"
+      - name: Install TeX Live . . .
         run: |
           packages=(
             texlive-latex-base
@@ -30,14 +30,14 @@ jobs:
           sudo apt-get install "${packages[@]}"
       - uses: gap-actions/setup-gap@v2
         env:
-          GAP_BOOTSTRAP: "minimal"
+          GAP_BOOTSTRAP: minimal
         with:
-          GAP_PKGS_TO_BUILD: ''
+          GAP_PKGS_TO_BUILD: ""
       - uses: gap-actions/build-pkg-docs@v1
-      - name: "Upload compiled manuals"
+      - name: Upload compiled manuals . . .
         uses: actions/upload-artifact@v4
         with:
-          name: "Digraphs manual"
+          name: Digraphs manual
           retention-days: 7
           path: |
             doc/manual.pdf
diff --git a/.github/workflows/os.yml b/.github/workflows/os.yml
new file mode 100644
index 000000000..7a19903e8
--- /dev/null
+++ b/.github/workflows/os.yml
@@ -0,0 +1,97 @@
+name: OS
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
+      - stable-*.*
+  schedule:
+    # Every day at 3:30 AM UTC
+    - cron: 30 3 * * *
+
+env:
+  DIGRAPHS_LIB: digraphs-lib-0.6
+  NO_COVERAGE: true
+
+jobs:
+  test-unix:
+    name: ${{ matrix.os }}${{ matrix.ABI }} / GAP stable-4.13
+    runs-on: ${{ matrix.os }}-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu
+            ABI: 32
+            pkgs-to-clone: digraphs/graphviz
+            pkgs-to-build: io orb datastructures grape
+          - os: macos
+            ABI: ""
+            pkgs-to-clone: NautyTracesInterface digraphs/graphviz
+            pkgs-to-build: io orb datastructures grape NautyTracesInterface
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Output g++ version . . .
+        run: g++ --version
+      - name: Install macOS dependencies . . .
+        if: ${{ runner.os == 'macOS' }}
+        run: brew install automake
+      - name: Install GAP and clone/compile necessary packages . . .
+        uses: gap-actions/setup-gap@v2
+        with:
+          GAP_PKGS_TO_CLONE: ${{ matrix.pkgs-to-clone }}
+          GAP_PKGS_TO_BUILD: ${{ matrix.pkgs-to-build }}
+          GAPBRANCH: stable-4.13
+          ABI: ${{ matrix.ABI }}
+      - name: Build Digraphs . . .
+        uses: gap-actions/build-pkg@v1
+        with:
+          ABI: ${{ matrix.ABI }}
+      - name: Install digraphs-lib . . .
+        run: |
+          curl --retry 5 -L -O "https://digraphs.github.io/Digraphs/${{ env.DIGRAPHS_LIB }}.tar.gz"
+          tar xf "${{ env.DIGRAPHS_LIB }}.tar.gz"
+      - name: Run DigraphsTestInstall . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/install.g
+      - name: Run DigraphsTestStandard . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/standard.g
+      - name: Run DigraphsTestManualExamples . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/examples.g
+      - name: Run DigraphsTestExtreme . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/extreme.g
+
+  test-cygwin:
+    name: cygwin / GAP stable-4.13
+    runs-on: windows-latest
+    env:
+      CHERE_INVOKING: 1
+    steps:
+      - uses: actions/checkout@v4
+      - uses: gap-actions/setup-cygwin@v1
+      - uses: gap-actions/setup-gap@cygwin-v2
+        with:
+          GAP_PKGS_TO_CLONE: NautyTracesInterface digraphs/graphviz
+          GAP_PKGS_TO_BUILD: io orb datastructures grape NautyTracesInterface
+          GAPBRANCH: stable-4.13
+      - uses: gap-actions/build-pkg@cygwin-v1
+      - name: Install digraphs-lib . . .
+        run: |
+          curl --retry 5 -L -O "https://digraphs.github.io/Digraphs/${{ env.DIGRAPHS_LIB }}.tar.gz"
+          tar xf "${{ env.DIGRAPHS_LIB }}.tar.gz"
+      - uses: gap-actions/run-pkg-tests@cygwin-v2
+        with:
+          NO_COVERAGE: true
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
new file mode 100644
index 000000000..7083cb5dc
--- /dev/null
+++ b/.github/workflows/ubuntu.yml
@@ -0,0 +1,79 @@
+name: Ubuntu
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - main
+      - stable-*.*
+  schedule:
+    # Every day at 3:30 AM UTC
+    - cron: 30 3 * * *
+
+env:
+  DIGRAPHS_LIB: digraphs-lib-0.6
+  NO_COVERAGE: true
+
+jobs:
+  test-unix:
+    name: Ubuntu / GAP ${{ matrix.gap-branch }} / ${{ matrix.only-needed && 'only-needed' || 'needed+suggested' }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        gap-branch:
+          - master
+          - stable-4.11
+          - stable-4.12
+          - stable-4.13
+        only-needed:
+          - true
+          - false
+        include:
+          - only-needed: true
+            pkgs-to-clone: digraphs/graphviz
+            pkgs-to-build: io orb datastructures
+          - only-needed: false
+            pkgs-to-clone: NautyTracesInterface digraphs/graphviz
+            pkgs-to-build: io orb datastructures grape NautyTracesInterface
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Output g++ version . . .
+        run: g++ --version
+      - name: Install GAP and clone/compile necessary packages . . .
+        uses: gap-actions/setup-gap@v2
+        with:
+          GAP_PKGS_TO_CLONE: ${{ matrix.pkgs-to-clone }}
+          GAP_PKGS_TO_BUILD: ${{ matrix.pkgs-to-build }}
+          GAPBRANCH: ${{ matrix.gap-branch }}
+      - name: Build Digraphs . . .
+        uses: gap-actions/build-pkg@v1
+      - name: Install digraphs-lib . . .
+        run: |
+          curl --retry 5 -L -O "https://digraphs.github.io/Digraphs/${{ env.DIGRAPHS_LIB }}.tar.gz"
+          tar xf "${{ env.DIGRAPHS_LIB }}.tar.gz"
+      - name: Run DigraphsTestInstall . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/install.g
+          only-needed: ${{ matrix.only-needed }}
+      - name: Run DigraphsTestStandard . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/standard.g
+          only-needed: ${{ matrix.only-needed }}
+      - name: Run DigraphsTestManualExamples . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/examples.g
+          only-needed: ${{ matrix.only-needed }}
+      - name: Run DigraphsTestExtreme . . .
+        uses: gap-actions/run-pkg-tests@v2
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/extreme.g
+          only-needed: ${{ matrix.only-needed }}
diff --git a/.github/workflows/valgrind.yml b/.github/workflows/valgrind.yml
new file mode 100644
index 000000000..0fa0315e3
--- /dev/null
+++ b/.github/workflows/valgrind.yml
@@ -0,0 +1,43 @@
+name: Valgrind
+on:
+  workflow_dispatch:
+  release:
+    types: [created]
+
+env:
+  VALGRIND: valgrind --trace-children=yes --leak-check=full --error-exitcode=1
+  NO_COVERAGE: true
+
+jobs:
+  test-valgrind:
+    name: Ubuntu / GAP stable-4.13 / valgrind
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Output g++ version . . .
+        run: g++ --version
+      - name: Install Valgrind . . .
+        run: sudo apt-get install valgrind
+      - name: Install GAP and clone/compile necessary packages . . .
+        uses: gap-actions/setup-gap@v2
+        with:
+          GAP_PKGS_TO_CLONE: NautyTracesInterface digraphs/graphviz
+          GAP_PKGS_TO_BUILD: io orb datastructures grape NautyTracesInterface
+          GAPBRANCH: stable-4.13
+          CONFIGFLAGS: --enable-valgrind
+      - name: Build Digraphs . . .
+        uses: gap-actions/build-pkg@v1
+      - name: Run DigraphsTestInstall . . .
+        # TODO: Replace below with gap-actions/run-pkg-tests@v2 if the functionality gets added
+        uses: ./.github/actions/test_with_valgrind
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/install.g
+          pre-gap: ${{ env.VALGRIND }}
+      - name: Run DigraphsTestStandard . . .
+        # TODO: Replace below with gap-actions/run-pkg-tests@v2 if the functionality gets added
+        uses: ./.github/actions/test_with_valgrind
+        with:
+          NO_COVERAGE: true
+          GAP_TESTFILE: tst/github_actions/standard.g
+          pre-gap: ${{ env.VALGRIND }}
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
deleted file mode 100644
index 927cfa82a..000000000
--- a/azure-pipelines.yml
+++ /dev/null
@@ -1,81 +0,0 @@
-pr:
-- main
-- stable-*.*
-
-trigger:
-- main
-- stable-*.*
-
-pool:
-  vmImage: 'ubuntu-latest'
-
-variables:
-    DIGRAPHS_LIB: digraphs-lib-0.6
-
-jobs:
-# TODO reinstate when this Docker container works again/we have a replacement
-#- job: ABI_64_GAP_master_PACKAGES_latest
-#  variables:
-#    SUITE: test
-#    ABI: 64
-#    GAP_VERSION: master
-#    PACKAGES: latest
-#  steps:
-#  - script: ci/azure-gap.sh
-#    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-# TODO there isn't a GAP master 32 docker container yet
-# - job: ABI_32_GAP_master_PACKAGES_latest
-#   variables:
-#     SUITE: test
-#     ABI: 32
-#     GAP_VERSION: master
-#     PACKAGES: latest
-#   steps:
-#   - script: ci/azure-gap.sh
-#     displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-- job: ABI_64_GAP_411_PACKAGES_latest
-  variables:
-    SUITE: test
-    ABI: 64
-    GAP_VERSION: 4.11.0
-    PACKAGES: latest
-  steps:
-  - script: ci/azure-gap.sh
-    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-- job: ABI_32_GAP_411_PACKAGES_latest
-  variables:
-    SUITE: test
-    ABI: 32
-    GAP_VERSION: 4.11.0
-    PACKAGES: latest
-  steps:
-  - script: ci/azure-gap.sh
-    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-- job: ABI_64_GAP_410_PACKAGES_required
-  variables:
-    SUITE: test
-    ABI: 64
-    GAP_VERSION: 4.10.2
-    PACKAGES: required
-  steps:
-  - script: ci/azure-gap.sh
-    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-- job: ABI_32_GAP_410_PACKAGES_required
-  variables:
-    SUITE: test
-    ABI: 32
-    GAP_VERSION: 4.10.2
-    PACKAGES: required
-  steps:
-  - script: ci/azure-gap.sh
-    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
-- job: coverage
-  variables:
-    SUITE: coverage
-    ABI: 64
-    GAP_VERSION: 4.11.0
-    PACKAGES: latest
-    THRESHOLD: 98
-  steps:
-  - script: ci/azure-gap.sh
-    displayName: 'Running the Digraphs package for GAP tests in docker container. . .'
diff --git a/ci/azure-gap.sh b/ci/azure-gap.sh
deleted file mode 100755
index 101313582..000000000
--- a/ci/azure-gap.sh
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/bin/bash
-set -e
-
-if [ "$GAP_VERSION" == "master" ]; then
-  CONTAINER_NAME="gapsystem/gap-docker-master"
-else
-  CONTAINER_NAME_BASE="jamesdbmitchell/gap-docker-minimal"
-  if [ "$ABI" == "32" ]; then
-    CONTAINER_NAME_BASE="$CONTAINER_NAME_BASE-32"
-  fi
-  CONTAINER_NAME="$CONTAINER_NAME_BASE:version-$GAP_VERSION"
-fi
-
-# Pull the docker container
-docker pull $CONTAINER_NAME 
-
-# Start the docker container detached
-ID=$(docker run --rm -i -d -e SUITE -e PACKAGES -e ABI -e DIGRAPHS_LIB -e GAP_VERSION -e THRESHOLD "$CONTAINER_NAME")
-
-# Get the GAP home directly from the container
-GAP_HOME=$(docker exec $ID bash -c 'echo "$GAP_HOME"')
-
-# Copy the digraphs directory into the container
-docker cp . $ID:$GAP_HOME/pkg/digraphs
-
-# Run the ci/docker-test.sh script in the running container
-docker exec -i $ID "$GAP_HOME/pkg/digraphs/ci/docker-test.sh" ; exit
-
-# Attach to the container
-docker attach $ID
diff --git a/ci/coverage.py b/ci/coverage.py
deleted file mode 100755
index b6657b5a6..000000000
--- a/ci/coverage.py
+++ /dev/null
@@ -1,70 +0,0 @@
-#!/usr/bin/env python3
-
-import tempfile, subprocess, sys, os, ntpath, re
-from os.path import exists, isdir, isfile
-
-_BLUE_PREFIX = '\033[34m'
-_RED_PREFIX = '\033[31m'
-_RESET = '\033[0m' 
-_ERR_PREFIX = _RED_PREFIX + 'coverage.py: error: '
-_WARN_PREFIX = _RED_PREFIX + 'coverage.py: warning: '
-
-def error_exit(msg):
-    print(_ERR_PREFIX + msg + _RESET)
-    sys.exit(1)
-
-def warn_exit(msg):
-    print(_WARN_PREFIX + msg + _RESET)
-    sys.exit(0)
-
-if len(sys.argv) != 3:
-    error_exit('arguments must be a test file and the threshold')
-
-f = str(sys.argv[1])
-if not (exists(f) and isfile(f)):
-    error_exit(f + ' does not exist!')
-
-threshold = int(sys.argv[2])
-
-_DIR = tempfile.mkdtemp()
-_COMMANDS = 'LoadPackage("digraphs", false); Test("' + f + '");;'
-_COMMANDS += 'outdir := "' + _DIR + '";;'
-_COMMANDS += '''
-UncoverageLineByLine();;
-LoadPackage("profiling", false);;
-filesdir := Concatenation(DIGRAPHS_Dir(), "/gap/");;
-x := ReadLineByLineProfile(Concatenation(outdir, "/profile.gz"));;
-OutputAnnotatedCodeCoverageFiles(x, filesdir, outdir);
-QUIT_GAP(0);
-'''
-
-_RUN_GAP = '../../gap -A -q -m 1g -o 2g -T --cover ' + _DIR + '/profile.gz -c "' + _COMMANDS.replace('"', '\\"') + '"'
-
-try:
-    pro = subprocess.Popen(_RUN_GAP, shell=True)
-    pro.wait()
-except KeyboardInterrupt:
-    pro.terminate()
-    pro.wait()
-    error_exit('Killed!')
-except (subprocess.CalledProcessError, IOError, OSError):
-    error_exit('Something went wrong calling GAP!')
-
-filename = _DIR + '/index.html'
-if not (exists(filename) and isfile(filename)):
-    error_exit('Failed to find file://' + filename)
-
-gi_file = ntpath.basename(f).split('.')[0] + '.gi'
-for line in open(filename):
-    if gi_file in line:
-        break
-
-search = re.search('coverage\d\d+[\'"]>(\d+)</td><td>([\d,]+)</td><td>([\d,]+)</td>', line)
-if search == None:
-    warn_exit('Could not find .gi file to which this .tst refers')
-
-percentage = search.group(1)
-print(_BLUE_PREFIX + gi_file + ' has ' + percentage + '% coverage: ' + search.group(2) + '/' + search.group(3) + ' lines' + _RESET)
-
-if int(percentage) < threshold:
-    warn_exit(percentage + '% is insufficient code coverage for ' + gi_file)
diff --git a/ci/docker-test.sh b/ci/docker-test.sh
deleted file mode 100755
index 9112abdab..000000000
--- a/ci/docker-test.sh
+++ /dev/null
@@ -1,214 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-set -o pipefail
-
-# This script is intended to be run inside a docker container
-# that already has GAP installed
-
-bold() {
-    printf "\033[1m%s\033[0m\n" "$*"
-}
-
-################################################################################
-# Check required environment variables are set
-################################################################################
-
-if [[ -z "${SUITE}" ]] ; then
-  bold "Error, environment variable SUITE is undefined"
-  exit 1
-fi
-
-if [[ -z "${GAP_HOME}" ]] ; then
-  bold "Error, environment variable GAP_HOME is undefined"
-  exit 1
-fi
-
-if [[ -z "${GAP_VERSION}" ]] ; then
-  bold "Error, environment variable GAP_VERSION is undefined"
-  exit 1
-fi
-
-if [[ -z "${DIGRAPHS_LIB}" ]] ; then
-  bold "Error, environment variable GAP_VERSION is undefined"
-  exit 1
-fi
-
-if [[ -z "${PACKAGES}" ]] ; then
-  bold "Error, environment variable GAP_VERSION is undefined"
-  exit 1
-fi
-
-if [ "$SUITE" == "coverage" ] && [ -z "${THRESHOLD}" ] ; then
-  bold "Error, environment variable THRESHOLD is undefined"
-  exit 1
-fi
-
-if [ "$SUITE" != "test" ] && [ "$SUITE" != "coverage" ] ; then
-  bold "Error, unrecognised suite: $SUITE"
-  exit 1
-fi
-
-env | grep -v "^LS_COLORS"
-
-################################################################################
-# Define globals
-################################################################################
-
-# Common curl settings
-CURL="curl --connect-timeout 5 --max-time 40 --retry 5 --retry-delay 0  -L"
-TESTLOG="$GAP_HOME/testlog.txt"
-GAPSH="$GAP_HOME/gap"
-DIG_DIR="$GAP_HOME/pkg/digraphs"
-
-################################################################################
-# Install system dependencies
-################################################################################
-
-bold "Installing dependencies (apt-get). . ."
-sudo apt-get --yes update
-sudo apt-get install libtool curl git xdg-utils --yes
-
-if [ "$GAP_VERSION" == "master" ]; then
-  # Stops the documentation from failing to compile because enumitem.sty isn't
-  # available
-  sudo apt-get remove texlive-latex-base --yes
-fi
-
-if [ "$SUITE" == "coverage" ]; then
-  sudo apt-get install python3 --yes
-fi
-
-bold "Fixing permissions . . . "
-sudo chown -R gap: $GAP_HOME/pkg/digraphs
-
-################################################################################
-# Compile Digraphs and install Digraphs lib
-################################################################################
-
-bold "Compiling the Digraphs package..."
-cd "$GAP_HOME/pkg/digraphs"
-
-aclocal --version
-autoconf --version
-autoheader --version
-
-./autogen.sh
-./configure $PKG_FLAGS $EXTRA_PKG_FLAGS
-make
-
-bold "Downloading $DIGRAPHS_LIB..."
-$CURL -O https://digraphs.github.io/Digraphs/$DIGRAPHS_LIB.tar.gz
-tar xf $DIGRAPHS_LIB.tar.gz
-rm $DIGRAPHS_LIB.tar.gz
-
-################################################################################
-# Install gap dependencies
-################################################################################
-
-bold "Installing GAP dependencies . . ."
-PKGS=( "io" "orb" "datastructures" )
-if [ "$GRAPE" != "no" ]; then
-  PKGS+=( "grape" )
-fi
-if [ "$SUITE" == "coverage" ]; then
-  PKGS+=( "profiling" )
-fi
-# We now need a newer GAPDoc than the one included in the Docker container for GAP 4.10.2
-if [ "$GAP_VERSION" == "4.10.2" ]; then
-  PKGS+=( "GAPDoc" )
-fi
-
-for PKG in "${PKGS[@]}"; do
-  cd $GAP_HOME/pkg
-
-  # Get the relevant version number
-  if [ "${PACKAGES[0]}" == "latest" ] || [ "$PKG" == "profiling" ]; then
-    VERSION=`$CURL -s "https://api.github.com/repos/gap-packages/${PKG}/releases" | grep tag_name | head -n 1 | awk -F'"' '{print $4}'`
-  else
-    VERSION=`grep "\"$PKG\"" $GAP_HOME/pkg/digraphs/PackageInfo.g | awk -F'"' '{print $4}' | cut -c3-`
-  fi
-
-  if [ -z $VERSION ]; then
-    bold "Could not determine the version number of the package $PKG!! Aborting..."
-    exit 1
-  elif [ "${VERSION:0:1}" == "v" ]; then
-    VERSION=${VERSION:1}
-  fi
-
-  # This can be removed when there is no GAPDoc special case for GAP 4.10.2
-  if [ "$PKG" == "GAPDoc" ]; then
-    URL="http://www.math.rwth-aachen.de/~Frank.Luebeck/GAPDoc/GAPDoc-$VERSION.tar.gz"
-  else
-    URL="https://github.com/gap-packages/$PKG/releases/download/v$VERSION/$PKG-$VERSION.tar.gz"
-  fi
-  bold "Downloading $PKG-$VERSION (${PACKAGES[0]} version), from URL:"
-  bold "$URL"
-  $CURL "$URL" -o $PKG-$VERSION.tar.gz
-  (tar xf $PKG-$VERSION.tar.gz && rm $PKG-$VERSION.tar.gz) || exit 1
-
-  if [ -f $PKG-$VERSION/configure ]; then
-    if [ "$PKG" == "orb" ] || [ "$PKG" == "grape" ] || [ "$PKG" == "datastructures" ]; then
-      cd $PKG-$VERSION && ./configure && make # orb/grape don't accept flags
-    else
-      cd $PKG-$VERSION && ./configure $PKG_FLAGS && make
-    fi
-  fi
-done
-
-################################################################################
-## Install NautyTracesInterface
-################################################################################
-if [ "$NAUTY" != "no" ]; then
-  bold "Getting master version of NautyTracesInterface . . ."
-  git clone -b master --depth=1 https://github.com/gap-packages/NautyTracesInterface.git $GAP_HOME/pkg/nautytraces
-  cd $GAP_HOME/pkg/nautytraces/nauty2*r* && ./configure $PKG_FLAGS && make
-  cd $GAP_HOME/pkg/nautytraces && ./autogen.sh && ./configure $PKG_FLAGS && make
-fi
-
-################################################################################
-## Run the tests
-touch $GAP_HOME/testlog.txt
-
-if [ "$SUITE" == "coverage" ]; then
-
-  bold "Performing code coverage tests..."
-  for TEST in $DIG_DIR/tst/standard/*.tst; do
-    FILENAME=${TEST##*/}
-    if [ ! `grep -E "$FILENAME" $DIG_DIR/.covignore` ]; then
-      $DIG_DIR/ci/coverage.py $TEST $THRESHOLD | tee -a $TESTLOG
-    else
-      bold "ignoring $FILENAME, which is listed in .covignore"
-    fi
-  done
-
-elif [ "$SUITE" == "test" ]; then
-
-  # Temporary workaround because of GAP being weird with memory
-  if [ "$ABI" == "32" ]; then
-    MEM=1g
-  elif [ "$ABI" == "64" ]; then
-    MEM=2g
-  fi
-
-  cd $DIG_DIR/tst/workspaces
-  bold "Running SaveWorkspace tests..."
-  echo "LoadPackage(\"digraphs\"); DigraphsTestInstall(); Test(\"save-workspace.tst\"); quit; quit; quit;" |
-    $GAPSH -A -m 768m -o $MEM -T 2>&1 | tee -a $TESTLOG
-
-  bold "Running LoadWorkspace tests..."
-  echo "Test(\"load-workspace.tst\"); DigraphsTestInstall(); quit; quit; quit;" |
-    $GAPSH -L test-output.w -A -x 80 -r -m 768m -o $MEM -T 2>&1 | tee -a $TESTLOG
-
-  bold "Running Digraphs package standard tests and manual examples..."
-  echo "LoadPackage(\"digraphs\"); DigraphsTestAll();" |
-    $GAPSH -A -x 80 -m 768m -o $MEM -T 2>&1 | tee -a $TESTLOG
-
-  if [ ! "$EXTREME" == "no" ]; then
-    bold "Running Digraphs package extreme tests..."
-    echo "LoadPackage(\"digraphs\"); DigraphsTestExtreme();" |
-      $GAPSH -A -x 80 -m 768m -o $MEM -T 2>&1 | tee -a $TESTLOG
-  fi
-fi
-
-( ! grep -E "Diff|brk>|#E|Error|Errors detected|# WARNING|Syntax warning|Couldn't open saved workspace|insufficient|WARNING in|FAILED|Total errors found:" $TESTLOG )
diff --git a/environment.yml b/environment.yml
deleted file mode 100644
index def1b5cfe..000000000
--- a/environment.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-name: digraphs
-
-channels:
-  - conda-forge
-
-dependencies:
-  - bliss
-  - planarity
diff --git a/src/cliques.c b/src/cliques.c
index dfd8f319b..d7b556e06 100644
--- a/src/cliques.c
+++ b/src/cliques.c
@@ -173,7 +173,7 @@ static void init_graph_from_digraph_obj(Graph* const graph, Obj digraph_obj) {
   Obj       adj_mat = FuncADJACENCY_MATRIX(0L, digraph_obj);
   DIGRAPHS_ASSERT(nr < MAXVERTS);
   DIGRAPHS_ASSERT(IS_PLIST(adj_mat));
-  DIGRAPHS_ASSERT(IS_PLIST(out));
+  DIGRAPHS_ASSERT(IS_PLIST(FuncOutNeighbours(0L, digraph_obj)));
   clear_graph(graph, nr);
 
   // Only include symmetric edges