I have a great deal of output from a procedure that I wrote clumsily.  How can I delete that output without highlighting and pressing the delete button.  Maple help is often of no help whatsoever.

I was introduced to DataFrame by some kind people here the other day and I thought I understood.  Then I tried this

M := DataFrame(<0,0,0;0,1,a;0,a,1>,rows=[0,1,a],columns=[0,1,a])

Now M[1, a] returns 0.  What's going on here? 

Consider this matrix

a b c

b c a

c a b

I would like to reference the entries with letters, not numbers.  The b,c entry would be a, for instance.  Any way to do this?

By default Maple labels vertices 1, 2, ...  and places these numbers within a circle making the position of the vertex.  Can one change the labels to, say, v1, v2, ... and place these outside the circles?  ..................Edgar

I asked a question about importing a matrix with symbolic entries the other day.  Just got email saying there had been a reply.  But I can't find my question or that reply!  ............Edgar