OEIS A034828 and OEIS A000292 (which give the Wiener index for the cycle graph and the path graph respectively) mention that 

However, 

GraphTheory:-WienerIndex(GraphTheory:-CycleGraph(19));
 = 
                               38

GraphTheory:-WienerIndex(GraphTheory:-PathGraph(20));
 = 
                               38

So what happened here? 

Consider the following exact algebraic number : 
 

Download wrong_minpoly.mw 
I would like to find its minimal polynomial (without a priori knowledge). 

According to the documentation, 

Regretfully, it is easy to see that the minimal polynomial of  cannot be the returned . And when I invoke  directly, the result is still not correct (and this evaluation takes a rather long time). 
Another help page mentions that 

However, as type(mp, polynom(rational, _X)) gives , we know that cannot be the desired minimal polynomial of either. 
So, what is the proper way to compute the minimal polynomial of  in Maple? 

Code: 

use alpha=1-(1/2)/(1-(RootOf(16*_Z*(_Z*(2*_Z*(_Z*(8*_Z*(_Z*(_Z*(_Z*(32*_Z*(8*_Z-33)+1513)-812)-13)+267)-1469)-330)+811)+279)+345,index=2)-1/2)**2) in 
	expr:=(1+alpha)*sqrt(1-alpha**2)+(3+4*alpha)/12*sqrt(3-4*alpha**2)+2*(1+alpha)/3*sqrt(2*(1+alpha)*(1-2*alpha))+(1+2*alpha)/6*sqrt(2*((1-alpha)**2-3*alpha**2)) 
end:
CodeTools:-Usage(PolynomialTools:-MinimalPolynomial(expr));

Of note, the minimal polynomial of an algebraic number  is the unique irreducible monic polynomial of smallest degree  with rational coefficients such that  and whose leading coefficient is 1. 

As the following worksheet shows, 
 

Download Why_not_consider_subexpressions?.mw

the underlined part is evidently not the simplest. (For instance, shouldn't  and  be converted into  and ?) 
If I understand correctly, , by default, should try combining every part of an expression with every other to apply a vast range of potential transformations to look at many different forms of it and make progress in picking out the simplest possible one. So, why is simplify unable to touch certain sub-expressions when they are encountered at intermediate stages in a computation? 

In my view, <x || (1 .. 2); y || (1 .. 2); 1 $ 2> should return a Matrix without any error messages; however, 

<x || (1 .. 2); y || (1 .. 2); 1 $ 2>; # Arguments are shielded??? 
Error, (in Matrix) this entry is too wide or too narrow: 1

If I understand right, each argument of a function is evaluated in turn (unless the modifier is used). 
So why is it not equivalent to <x1, x2; y1, y2; 1, 1>? 

I am trying to get Maple to simplify the following trigonometric expressions (for "generic" parameters) as much as possible: 

sineExpr(3) := (
   sin(a[2] - b[1])*sin(a[3] - b[1]))/(
   sin(b[2] - b[1])*sin(b[3] - b[1]))*sin(a[1] - b[1]) + (
   sin(a[3] - b[2])*sin(a[1] - b[2]))/(
   sin(b[3] - b[2])*sin(b[1] - b[2]))*sin(a[2] - b[2]) + (
   sin(a[1] - b[3])*sin(a[2] - b[3]))/(
   sin(b[1] - b[3])*sin(b[2] - b[3]))*sin(a[3] - b[3]);
 = 
   


sineExpr(4) := (
   sin(a[2] - b[1])*sin(a[3] - b[1])*sin(a[4] - b[1]))/(
   sin(b[2] - b[1])*sin(b[3] - b[1])*sin(b[4] - b[1]))*
   sin(a[1] - b[1]) + (
   sin(a[3] - b[2])*sin(a[4] - b[2])*sin(a[1] - b[2]))/(
   sin(b[3] - b[2])*sin(b[4] - b[2])*sin(b[1] - b[2]))*
   sin(a[2] - b[2]) + (
   sin(a[4] - b[3])*sin(a[1] - b[3])*sin(a[2] - b[3]))/(
   sin(b[4] - b[3])*sin(b[1] - b[3])*sin(b[2] - b[3]))*
   sin(a[3] - b[3]) + (
   sin(a[1] - b[4])*sin(a[2] - b[4])*sin(a[3] - b[4]))/(
   sin(b[1] - b[4])*sin(b[2] - b[4])*sin(b[3] - b[4]))*
   sin(a[4] - b[4]);
 = 

So far, all of my attempts have failed: 
 

Download sinIdentity.mw

Note that because zero testing is frequently considerably easier, combine always succeeds in showing that the difference between the simplest possible and the original version is zero. 

combine(sin((a[1]+a[2]+a[3])-(b[1]+b[2]+b[3]))-sineExpr(3));
 = 
                               0

combine(sin((a[1]+a[2]+a[3]+a[4])-(b[1]+b[2]+b[3]+b[4]))-sineExpr(4));
 = 
                               0

However, I wonder if Maple can thoroughly simplify them without knowing those known “simplest possible” form beforehand. 
I also tried some other functions like rationalize, radnormal, and `convert/trig`, yet Maple appears to have not been capable of completely simplifying even the sub-simplest case 𝑚＝2. Is there any workaround? 

Of note, it can be demonstrated inductively that ∀m∈ℕ_₊ 

where none of the denominators is 0. Nevertheless, as mentioned above, is it possible to transform  and  (as well as , if possible) into potentially more elegant forms (Ideally,  is rewritten into ,  is rewritten into , and  is rewritten into .) without any such a priori knowledge? 
In Mma, these may be done using TrigReduce directly (cf. ); unfortunately, I cannot found a Maple equivalent to such functionality.