Merge pull request #14 from jw-allen/v6.2

v0.6.2

Author: jw-allen

README

@@ -1,10 +1,10 @@
 +--------------------------------------------------------+--------------------+
 |                                                        | Copyright (C) 2020 |
-|                   SBStrips  (v0.6.1)                   |          Joe Allen |
+|                   SBStrips  (v0.6.2)                   |          Joe Allen |
 |                                                        |       [he/him/his] |
 +--------------------------------------------------------+--------------------+
 
-This is the README file for SBStrips (v0.6.1), which is a package for GAP 4.11.
+This is the README file for SBStrips, which is a package for GAP 4.11.
 
 +--+ About +------------------------------------------------------------------+
 The SBStrips package models 'strings', namely the decorated graphs used in
@@ -28,9 +28,9 @@ The SBStrips can be installed by following these steps (assuming you already
 have GAP installed.)
 
     1. Download the archive file 
-            sbstrips/archive/v0.6.1.tar.gz
+            sbstrips/archive/v0.6.2.tar.gz
        from
-            https://github.com/jw-allen/sbstrips/archive/v0.6.1.tar.gz
+            https://github.com/jw-allen/sbstrips/archive/v0.6.2.tar.gz
 
     2. Unpack it into your  pkg  directory. It should create a subdirectory
        called  sbstrips.

doc/main.xml

@@ -13,7 +13,7 @@
     <!ENTITY QPA "<Package>QPA</Package>">
     <!ENTITY SBStrips "<Package>SBStrips</Package>"> 
     <!ENTITY true "<K>true</K>">
-    <!ENTITY VERSION "0.6.1">
+    <!ENTITY VERSION "0.6.2">
     ]
   >
 

lib/1reg.gd

@@ -97,3 +97,18 @@ DeclareOperation( "PathBySourceAndLength", [ IsQuiverVertex, IsInt ] );
 ##  </ManSection>
 ##  <#/GAPDoc>  
 DeclareOperation( "PathByTargetAndLength", [ IsQuiverVertex, IsInt ] );
+
+##  <#GAPDoc Label="DocIs2RegQuiver">
+##  <ManSection>
+##    <Prop Name="Is2RegQuiver" Arg="quiver"/>
+##    <Description>
+##      Argument: <A>quiver</A>, a quiver
+##      <Br />
+##    </Description>
+##    <Returns>
+##      either <C>true</C> or <C>false</C>, depending on whether or not
+##      <A>quiver</A> is <M>2</M>-regular.
+##    </Returns>
+##  </ManSection>
+##  <#/GAPDoc>
+DeclareProperty( "Is2RegQuiver", IsQuiver );

lib/1reg.gi

@@ -20,6 +20,28 @@ InstallMethod(
     end
 );
 
+InstallMethod(
+    Is2RegQuiver,
+    "for quivers",
+    [IsQuiver],
+    function( quiver )
+        local
+            v,      # Vertex variable
+            verts;  # Vertices of <quiver>
+        
+        # Test vertex degrees
+        verts := VerticesOfQuiver( quiver );
+		
+        for v in verts do
+            if InDegreeOfVertex( v ) <> 2 or OutDegreeOfVertex( v ) <> 2 then
+                return false;
+            fi;
+        od;
+		
+        return true;
+    end
+);
+
 InstallMethod(
     1RegQuivIntActionFunction,
     "for 1-regular quivers",