I want to simplify the following expression to 2a-2bk+k(n+6). But the following command is invalid.

However, the above expression can be simplified when k is fixed to a number, such as k=2.

I wonder what went wrong.

It seems to be recognized only if n1+ n2 is combined.

Recently I saw a heated discussion on this post：https://www.mapleprimes.com/questions/233026-Write-Output-Of-For-Loop-To-txt-File

In Carl Love  's answer, I felt the power of adjacency matrix of graph. I carefully read maple's function to generate non IsomorphicGraphs:  NonIsomorphicGraphs. There was one passage that I thought was really interesting.

I never quite understood what the advantage of this bits was. At least according to the help documentation, we have  to do many works to do to convert this into a adjacency matrix of graph.

[NonIsomorphicGraphs(8, output = graphs, restrictto = regular[2])]

bit := Vector[row](Bits:-Split(210256131, bits = (8*(8 - 1))/2));
M := Matrix(8, 8, shape = symmetric, datatype = integer[1]);
M[1, 2 .. 8] := bit[1 .. 7];

M[2, 3 .. 8] := bit[8 .. 13];

M[3, 4 .. 8] := bit[14 .. 18];
M[4, 5 .. 8] := bit[19 .. 22];

M[5, 6 .. 8] := bit[23 .. 25];

M[6, 7 .. 8] := bit[26 .. 27];
M[7, 8 .. 8] := bit[28 .. 28];
M;

From adjacency matrix of graph,  we can diractly get a lot of information about the graph, like edges, and the number of closed walks of a particular length, but from bits , what imformation of graph we can get?

If we have to convert it to an adjacency matrix fist, maybe it's a little bit more complicated from above long codes. At least there isn't a more efficient way to convert?

I know that the "rotate" can rotate image of a function, but we see that the coordinate axes don't change as much. For example:

Although someone seems to have asked a similar question a long time ago, it was far from what I needed.

https://www.mapleprimes.com/questions/97812-Flip-Plot-Exchange-X-And-Yaxes

What I want to do is rotate the axes and the image at the same time rather than just flip axes.  The schematic diagram is as follows.

I drew a polygon using some point coordinates combined with the pointplot.

I ‘d like to add  label  of endpoints to polygons, although I did this via textplot, but it didn't feel very neat. I hope when the polygon is drawn, labels of  every endpoints appear . These labels are the names of the assignment variable for the coordinates of the endpoints.

I think  DrawGraph command  in graph theory package  is very good to achieve this in a sense. 

In mathematica, CommunityGraphPlot attempts to draw the vertices grouped into communities. 

This function is very useful, for example, if I get a partition of vertices, such as the gallai-Edmonds decomposition below, I use  CommunityGraphPlot to easily see the overall layout of the graph. I don't know if Maple has a corresponding function.