<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IsMutableDigraph</code></td><td class="tdright">( category )</td></tr></table></div>
<p><code class="code">IsMutableDigraph</code> is a synonym for <code class="func">IsDigraph</code> (<a href="chap3_mj.html#X7877ADC77F85E630"><span class="RefLink">3.1-1</span></a>) and <code class="func">IsMutable</code> (<a href="/home/runner/gap/doc/ref/chap12_mj.html#X7999AD1D7A4F1F46"><span class="RefLink">Reference: IsMutable</span></a>). A mutable digraph may be changed in-place by methods in the <strong class="pkg">Digraphs</strong> package, and is not attribute-storing – see <code class="func">IsAttributeStoringRep</code> (<a href="/home/runner/gap/doc/ref/chap13_mj.html#X7A951C33839AF2C1"><span class="RefLink">Reference: IsAttributeStoringRep</span></a>).</p>
<p>A mutable digraph may be converted into an immutable attribute-storing digraph by calling <code class="func">MakeImmutable</code> (<a href="/home/runner/gap/doc/ref/chap12_mj.html#X80CE136D804097C7"><span class="RefLink">Reference: MakeImmutable</span></a>) on the digraph.</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IsImmutableDigraph</code></td><td class="tdright">( category )</td></tr></table></div>
<p><code class="code">IsImmutableDigraph</code> is a subcategory of <code class="func">IsDigraph</code> (<a href="chap3_mj.html#X7877ADC77F85E630"><span class="RefLink">3.1-1</span></a>). Digraphs that lie in <code class="code">IsImmutableDigraph</code> are immutable and attribute-storing. In particular, they lie in <code class="func">IsAttributeStoringRep</code> (<a href="/home/runner/gap/doc/ref/chap13_mj.html#X7A951C33839AF2C1"><span class="RefLink">Reference: IsAttributeStoringRep</span></a>).</p>
<p>A mutable digraph may be converted to an immutable digraph that lies in the category <code class="code">IsImmutableDigraph</code> by calling <code class="func">MakeImmutable</code> (<a href="/home/runner/gap/doc/ref/chap12_mj.html#X80CE136D804097C7"><span class="RefLink">Reference: MakeImmutable</span></a>) on the digraph.</p>
<p>The operation <code class="func">DigraphMutableCopy</code> (<a href="chap3_mj.html#X83D93A8A8251E6F9"><span class="RefLink">3.3-1</span></a>) can be used to construct a mutable copy of an immutable digraph. It is however not possible to convert an immutable digraph into a mutable digraph in-place.</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IsCayleyDigraph</code></td><td class="tdright">( category )</td></tr></table></div>
<p><code class="code">IsCayleyDigraph</code> is a subcategory of <code class="code">IsDigraph</code>. Digraphs that are Cayley digraphs of a group and that are constructed by the operation <code class="func">CayleyDigraph</code> (<a href="chap3_mj.html#X7FCADADC7EC28478"><span class="RefLink">3.1-12</span></a>) are constructed in this category, and are always immutable.</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IsDigraphWithAdjacencyFunction</code></td><td class="tdright">( category )</td></tr></table></div>
<p><code class="code">IsDigraphWithAdjacencyFunction</code> is a subcategory of <code class="code">IsDigraph</code>. Digraphs that are <em>created</em> using an adjacency function are constructed in this category.</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ DigraphByOutNeighboursType</code></td><td class="tdright">( global variable )</td></tr></table></div>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ DigraphFamily</code></td><td class="tdright">( family )</td></tr></table></div>
<p>The type of all digraphs is <code class="code">DigraphByOutNeighboursType</code>. The family of all digraphs is <code class="code">DigraphFamily</code>.</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<dl>
<dt><strong class="Mark">for a list (i.e. an adjacency list)</strong></dt>
<dd><p>if <var class="Arg">obj</var> is a list of lists of positive integers in the range from <code class="code">1</code> to <code class="code">Length(<var class="Arg">obj</var>)</code>, then this function returns the digraph with vertices <span class="SimpleMath">\(E ^ 0 = \)</span><code class="code">[1 .. Length(<var class="Arg">obj</var>)]</code>, and edges corresponding to the entries of <var class="Arg">obj</var>.</p>
<p>More precisely, there is an edge from vertex <code class="code">i</code> to <code class="code">j</code> if and only if <code class="code">j</code> is in <code class="code"><var class="Arg">obj</var>[i]</code>; the source of this edge is <code class="code">i</code> and the range is <code class="code">j</code>. If <code class="code">j</code> occurs in <code class="code"><var class="Arg">obj</var>[i]</code> with multiplicity <code class="code">k</code>, then there are <code class="code">k</code> edges from <code class="code">i</code> to <code class="code">j</code>.</p>
</dd>
<dt><strong class="Mark">for three lists</strong></dt>
<dd><p>if <var class="Arg">obj</var> is a duplicate-free list, and <var class="Arg">source</var> and <var class="Arg">range</var> are lists of equal length consisting of positive integers in the list <code class="code">[1 .. Length(<var class="Arg">obj</var>)]</code>, then this function returns a digraph with vertices <span class="SimpleMath">\(E ^ 0 = \)</span><code class="code">[1 .. Length(<varclass="Arg">obj</var>)]</code>, and <code class="code">Length(<var class="Arg">source</var>)</code> edges. For each <code class="code">i</code> in <code class="code">[1 .. Length(<var class="Arg">source</var>)]</code> there exists an edge with source vertex <code class="code">source[i]</code> and range vertex <code class="code">range[i]</code>. See <code class="func">DigraphSource</code> (<a href="chap5_mj.html#X7FDEBF3279759961"><span class="RefLink">5.2-5</span></a>) and <code class="func">DigraphRange</code> (<a href="chap5_mj.html#X7FDEBF3279759961"><span class="RefLink">5.2-5</span></a>).</p>
<p>The vertices of the digraph will be labelled by the elements of <var class="Arg">obj</var>.</p>
</dd>
<dt><strong class="Mark">for an integer, and two lists</strong></dt>
<dd><p>if <var class="Arg">obj</var> is an integer, and <var class="Arg">source</var> and <var class="Arg">range</var> are lists of equal length consisting of positive integers in the list <code class="code">[1 .. <var class="Arg">obj</var>]</code>, then this function returns a digraph with vertices <span class="SimpleMath">\(E ^ 0 = \)</span><code class="code">[1 .. <var class="Arg">obj</var>]</code>, and <code class="code">Length(<var class="Arg">source</var>)</code> edges. For each <code class="code">i</code> in <code class="code">[1 .. Length(<var class="Arg">source</var>)]</code> there exists an edge with source vertex <code class="code">source[i]</code> and range vertex <code class="code">range[i]</code>. See <code class="func">DigraphSource</code> (<a href="chap5_mj.html#X7FDEBF3279759961"><span class="RefLink">5.2-5</span></a>) and <code class="func">DigraphRange</code> (<a href="chap5_mj.html#X7FDEBF3279759961"><span class="RefLink">5.2-5</span></a>).</p>
</dd>
<dt><strong class="Mark">for a list and a function</strong></dt>
<dd><p>if <var class="Arg">list</var> is a list and <var class="Arg">func</var> is a function taking 2 arguments that are elements of <var class="Arg">list</var>, and <var class="Arg">func</var> returns <code class="keyw">true</code> or <code class="keyw">false</code>, then this operation creates a digraph with vertices <code class="code">[1 .. Length(<var class="Arg">list</var>)]</code> and an edge from vertex <code class="code">i</code> to vertex <code class="code">j</code> if and only if <code class="code"><var class="Arg">func</var>(<var class="Arg">list</var>[i], <var class="Arg">list</var>[j])</code> returns <code class="keyw">true</code>.</p>
</dd>
<dt><strong class="Mark">for a group, a list, and two functions</strong></dt>
<dd><p>The arguments will be <var class="Arg">G, list, act, adj</var>.</p>
<p>Let <var class="Arg">G</var> be a group acting on the objects in <var class="Arg">list</var> via the action <var class="Arg">act</var>, and let <var class="Arg">adj</var> be a function taking two objects from <var class="Arg">list</var> as arguments and returning <code class="code">true</code> or <code class="code">false</code>. The function <var class="Arg">adj</var> will describe the adjacency between objects from <var class="Arg">list</var>, which is invariant under the action of <var class="Arg">G</var>. This variant of the constructor returns a digraph with vertices the objects of <var class="Arg">list</var> and directed edges <code class="code">[x, y]</code> when <code class="code">f(x, y)</code> is <code class="code">true</code>.</p>
<p>The action of the group <var class="Arg">G</var> on the objects in <var class="Arg">list</var> is stored in the attribute <code class="func">DigraphGroup</code> (<a href="chap7_mj.html#X803ACEDA7BBAC5B3"><span class="RefLink">7.2-10</span></a>), and is used to speed up operations like <code class="func">DigraphDiameter</code> (<a href="chap5_mj.html#X7F16B9EB8398459C"><span class="RefLink">5.4-1</span></a>).</p>
</dd>
<dt><strong class="Mark">for a Grape package graph</strong></dt>
<dd><p>if <var class="Arg">obj</var> is a <span class="URL"><a href="https://gap-packages.github.io/grape">GRAPE</a></span> package graph (i.e. a record for which the function <code class="code">IsGraph</code> returns <code class="keyw">true</code>), then this function returns a digraph isomorphic to <var class="Arg">obj</var>.</p>
</dd>
<dt><strong class="Mark">for a binary relation</strong></dt>
<dd><p>if <var class="Arg">obj</var> is a binary relation on the points <code class="code">[1 .. n]</code> for some positive integer <span class="SimpleMath">\(n\)</span>, then this function returns the digraph defined by <var class="Arg">obj</var>. Specifically, this function returns a digraph which has <span class="SimpleMath">\(n\)</span> vertices, and which has an edge with source <code class="code">i</code> and range <code class="code">j</code> if and only if <code class="code">[i,j]</code> is a pair in the binary relation <var class="Arg">obj</var>.</p>
</dd>
<dt><strong class="Mark">for a string naming a digraph</strong></dt>
<dd><p>if <var class="Arg">obj</var> is a non-empty string, then this function returns the digraph that has name <var class="Arg">obj</var>. <strong class="pkg">Digraphs</strong> comes with a database containing a few hundred common digraph names that can be loaded in this way. Valid names include <code class="code">"folkman"</code>, <code class="code">"diamond"</code> and <code class="code">"brinkmann"</code>. If the name is commonly followed by the word <code class="code">"graph"</code>, then it is called without writing <code class="code">"graph"</code> at the end. You can explore the available graph names using <code class="func">ListNamedDigraphs</code> (<a href="chap3_mj.html#X7BB820C9813F035F"><span class="RefLink">3.1-13</span></a>). Digraph names are case and whitespace insensitive.</p>
<p>Note that any undirected graphs in the database are stored as symmetric digraphs, so the resulting digraph will have twice as many edges as its undirected counterpart.</p>
<p>The next example illustrates the uses of the fourth and fifth variants of this constructor. The resulting digraph is a strongly regular graph, and it is actually the point graph of the van Lint-Schrijver partial geometry, <a href="chapBib_mj.html#biBvLS81">[vLS81]</a>. The algebraic description is taken from the seminal paper of Calderbank and Kantor <a href="chapBib_mj.html#biBCK86">[CK86]</a>.</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<p>If <var class="Arg">list</var> is the adjacency matrix of a digraph in the sense of <code class="func">AdjacencyMatrix</code> (<a href="chap5_mj.html#X7DC2CD70830BEE60"><span class="RefLink">5.2-1</span></a>), then this operation returns the digraph which is defined by <var class="Arg">list</var>.</p>
<p>Alternatively, if <var class="Arg">list</var> is a square boolean matrix, then this operation returns the digraph with <code class="code">Length(</code><var class="Arg">list</var><code class="code">)</code> vertices which has the edge <code class="code">[i,j]</code> if and only if <var class="Arg">list</var><code class="code">[i][j]</code> is <code class="keyw">true</code>.</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<p>If <var class="Arg">list</var> is list of pairs of positive integers, then this function returns the digraph with the minimum number of vertices <code class="code">m</code> such that its list equal <var class="Arg">list</var>.</p>
<p>If the optional second argument <var class="Arg">n</var> is a positive integer with <code class="code"><var class="Arg">n</var> >= m</code> (with <code class="code">m</code> defined as above), then this function returns the digraph with <var class="Arg">n</var> vertices and list <var class="Arg">list</var>.</p>
<p>If <var class="Arg">G</var> is a permutation group, <var class="Arg">edges</var> is an edge or list of edges, and <var class="Arg">n</var> is a non-negative integer such that <var class="Arg">G</var> fixes <code class="code">[1 .. <var class="Arg">n</var>]</code> setwise, then this operation returns an immutable digraph with <var class="Arg">n</var> vertices and the union of the orbits of the edges in <var class="Arg"> edges </var> under the action of the permutation group <var class="Arg">G</var>. An edge in this context is simply a pair of positive integers.</p>
<p>If the optional third argument <var class="Arg">n</var> is not present, then the largest moved point of the permutation group <var class="Arg">G</var> is used by default.</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<p>If <var class="Arg">list</var> is a list of lists of positive integers list the range <code class="code">[1 .. Length(<var class="Arg">list</var>)]</code>, then this function returns the digraph with vertices <span class="SimpleMath">\(E^0=\)</span><code class="code">[1 .. Length(<var class="Arg">list</var>)]</code>, and edges corresponding to the entries of <var class="Arg">list</var>. More precisely, there is an edge with source vertex <code class="code">i</code> and range vertex <codeclass="code">j</code> if <code class="code">i</code> is in the list <code class="code"><var class="Arg">list</var>[j]</code>.</p>
<p>If <code class="code">i</code> occurs in the list <code class="code"><var class="Arg">list</var>[j]</code> with multiplicity <code class="code">k</code>, then there are <code class="code">k</code> multiple edges from <code class="code">i</code> to <code class="code">j</code>.</p>
<p>Let <var class="Arg">G</var> be any group and let <var class="Arg">gens</var> be a list of elements of <var class="Arg">G</var>. This operation returns a digraph that corresponds to the Cayley graph of <var class="Arg">G</var> with respect to <var class="Arg">gens</var>.</p>
<p>The vertices of the digraph correspond to the elements of <var class="Arg">G</var>, in the order given by <code class="code">Set(<var class="Arg">G</var>)</code>. There exists an edge from vertex <code class="code">u</code> to vertex <code class="code">v</code> if and only if there exists a generator <code class="code">g</code> in <var class="Arg">gens</var> such that <code class="code">Set(<var class="Arg">G</var>)[u] * g = Set(<var class="Arg">G</var>)[v]</code>.</p>
<p>The labels of the vertices <code class="code">u</code>, <code class="code">v</code>, and the edge <code class="code">[u, v]</code> are the corresponding elements <code class="code">AsList(<var class="Arg">G</var>)[u]</code>, <code class="code">AsList(<var class="Arg">G</var>)[v]</code>, and generator <code class="code">g</code>, respectively; see <code class="func">DigraphVertexLabel</code> (<a href="chap5_mj.html#X7CA91E4B7904F793"><span class="RefLink">5.1-11</span></a>) and <code class="func">DigraphEdgeLabel</code> (<a href="chap5_mj.html#X79FAEACC7F438C2F"><span class="RefLink">5.1-13</span></a>).</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<p>If the optional third argument <var class="Arg">gens</var> is not present, then the generators of <var class="Arg">G</var> are used by default.</p>
<p>The digraph created by this operation belongs to the category <code class="func">IsCayleyDigraph</code> (<a href="chap3_mj.html#X7E749324800B38A5"><span class="RefLink">3.1-4</span></a>), the group <var class="Arg">G</var> can be recovered from the digraph using <code class="func">GroupOfCayleyDigraph</code> (<a href="chap5_mj.html#X7A000B1D7CCF7093"><span class="RefLink">5.5-1</span></a>), and the generators <var class="Arg">gens</var> can be obtained using <code class="func">GeneratorsOfCayleyDigraph</code> (<a href="chap5_mj.html#X8528455987D7D2BF"><span class="RefLink">5.5-2</span></a>).</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ ListNamedDigraphs</code>( <var class="Arg">s</var>[, <var class="Arg">level</var>] )</td><td class="tdright">( operation )</td></tr></table></div>
<p>Returns: A list of strings representing digraph names.</p>
<p>This function searches through the list of names that are currently in the <strong class="pkg">Digraphs</strong> database of named digraphs. The first argument <var class="Arg">s</var> should be a partially completed string; this function returns all completions <code class="code">str</code> of the string <var class="Arg">s</var> such that <code class="code">Digraph(str)</code> will successfully return a digraph.</p>
<p>The optional second argument <var class="Arg">level</var> controls the flexibility of the search. If <code class="code"><var class="Arg">level</var> = 1</code>, then only strings beginning exactly with <var class="Arg">s</var> are returned. If <code class="code"><var class="Arg">level</var> = 2</code>, then all names containing <var class="Arg">s</var> as a substring are returned. If <code class="code"><var class="Arg">level</var> = 3</code>, then once again a substring search is carried out, but characters that are not alphanumeric are ignored in the search.</p>
<p>If <var class="Arg">level</var> is not specified, it is set by default to equal 2.</p>
<p>The search is always case and whitespace insensitive, and this is also the case when applying <code class="func">Digraph</code> (<a href="chap3_mj.html#X834843057CE86655"><span class="RefLink">3.1-7</span></a>) to a string.</p>
<p>If <var class="Arg">digraph</var> is a digraph with a positive number of vertices <span class="SimpleMath">\(n\)</span>, and no multiple edges, then this operation returns a binary relation on the points <code class="code">[1..n]</code>. The pair <code class="code">[i,j]</code> is in the binary relation if and only if <code class="code">[i,j]</code> is an edge in <var class="Arg">digraph</var>.</p>
</dd>
</dl>
<p>and <var class="Arg">n</var> is a non-negative integer, then <code class="code">AsDigraph</code> attempts to construct a digraph with <var class="Arg">n</var> vertices whose edges are determined by <var class="Arg">f</var>.</p>
<p>The digraph returned by <code class="code">AsDigraph</code> has for each vertex <code class="code">v</code> in <code class="code">[1 .. <var class="Arg">n</var>]</code>, an edge with source <code class="code">v</code> and range <code class="code">v ^ <var class="Arg">f</var></code>. If <code class="code">v ^ <var class="Arg">f</var></code> is greater than <var class="Arg">n</var> for any <code class="code">v</code>, then <code class="keyw">fail</code> is returned.</p>
<p>If the optional second argument <var class="Arg">n</var> is not supplied, then the degree of the transformation <var class="Arg">f</var>, the largest moved point of the permutation <var class="Arg">f</var>, the maximum of the degree and the codegree of the partial perm <var class="Arg">f</var>, or as applicable, is used by default.</p>
<p>If the optional first argument <var class="Arg">filt</var> is present, then this should specify the category or representation the digraph being created will belong to. For example, if <var class="Arg">filt</var> is <code class="func">IsMutableDigraph</code> (<a href="chap3_mj.html#X7D7EDF83820ED6F5"><span class="RefLink">3.1-2</span></a>), then the digraph being created will be mutable, if <var class="Arg">filt</var> is <code class="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>), then the digraph will be immutable. If the optional first argument <var class="Arg">filt</var> is not present, then <codeclass="func">IsImmutableDigraph</code> (<a href="chap3_mj.html#X7CAFAA89804F80BD"><span class="RefLink">3.1-3</span></a>) is used by default.</p>
<p>If <var class="Arg">digraph</var> is a mutable or immutable digraph without multiple edges, then this operation returns a <span class="URL"><a href="https://gap-packages.github.io/grape">GRAPE</a></span> package graph that is isomorphic to <var class="Arg">digraph</var>.</p>
<p>If <var class="Arg">digraph</var> is a multidigraph, then since <span class="URL"><a href="https://gap-packages.github.io/grape">GRAPE</a></span> does not support multiple edges, the multiple edges will be reduced to a single edge in the result. In order words, for a multidigraph this operation will return the same as <code class="code">Graph(DigraphRemoveAllMultipleEdges(</code><var class="Arg">digraph</var><code class="code">))</code>.</p>
