Examples of Symbolic Index Tensor Calculus

Sections in this chapter:

Introduction
Riemann Rules
Bianchi II hard force demonstration

For other chapters go to Index

 Introduction

 This chapter is devoted to  show how TTC works in symbolic index tensor calculus. We have choosed two conceptually simple examples which are known for all people which have studied differential geometry and special riemann tensor properties.

Both sections shows how TTC recognice the properties of a defined tensor and applies them in a sistematic way to reach the result.

 RiemannRules

 Here we show how TTC handle with riemann rules in symbolic calculations automatically. That is TTC don't have any kind of library with the rules listed. It simple applies their algorithms of canonisation over the expression to handle. We use the fucntion SimplifyAllIndex[2] which simplify and store all rules related to the calculation for further use. It is possible to save this rules on a file and use them in other sessions. See IniSimplifyAllIndexSave.The name of rule (RiemannRule##) are traced from the book guide of MathTensor package.

<<path/ttc.m

 ----------------------------------------
|TTC: Tools of Tensor Calculus 4.3.1|
| A.Balfagon,P.Castellvi and X.Jaen |
| http://baldufa.upc.edu/ttc |
| e-mail:Xavier.Jaen@upc.edu |
| version: june, 1, 2005 |
----------------------------------------
| TTC works correctly with |
| Cell menu options: |
| Default Input FormatType=InputForm |
| Default Output FormatType=OutputForm |
----------------------------------------
| Session started on |
| June, 5 , 2005 |
| at 17 h 50 min 6.981 s |
----------------------------------------

InputSMetric[gn,XX,"g",g]
 CPU Time=0.11 s Memory in use=2.47 Mb
     {g}

InputSRiemann[gn,XX,"R",Rie,Ric,R]
 CPU Time=0.27 s Memory in use=2.512 Mb
     {g, Rie, Ric, R}

InputIndex[{i,j,k,l,m,n,o,p,q,r,s,t}]
 CPU Time=0. s Memory in use=2.512 Mb
     {i, j, k, l, m, n, o, p, q, r, s, t}

RiemannRule1
RR1=Rie[-a,a,-c,-d]//Index[gn]
 CPU Time=0.22 s Memory in use=2.525 Mb
                k
     0     + R
      i j     k   i j
RR1//Index[gn,SimplifyAllIndex[2]]
 CPU Time=0.22 s Memory in use=2.534 Mb
     0

RiemannRule6
RR6=Rie[-a,-b,-c,-d] Ric[a,b]//Index[gn]
 CPU Time=0.22 s Memory in use=2.528 Mb
              k l
     0     + R     R
      i j           k l i j
RR6//Index[gn,SimplifyAllIndex[2]]
CPU Time=1.98 s Memory in use=2.562 Mb
     0
RiemannRule7
RR7= Rie[-a,-b,-c,-d] Rie[-e,a,b,c]+
1/2 Rie[-p,-d,-q,-r] Rie[-e,p,q,r]//Index[gn]
 CPU Time=0.38 s Memory in use=2.538 Mb
                k l m
             R         R
              j         k i l m
     0     + ------------------- +
      i j             2

          k l m
       R         R
        j         k l m i

  RR7//Index[gn,SimplifyAllIndex[2]]
CPU Time=61.9 s Memory in use=2.647 Mb
     0
RiemannRule8
RR8=Rie[-a,-b,-c,-d] Rie[a,c,b,h]-
1/2 Rie[-p,-d,-q,-r] Rie[p,h,q,r]//Index[gn]
 CPU Time=0.38 s Memory in use=2.562 Mb
                        k j l m
             R         R
        j     k i l m
     0     - ------------------- +
      i               2

                  k m l j
       R         R
        k l m i
RR8//Index[gn,SimplifyAllIndex[2]]
 CPU Time=0.94 s Memory in use=2.649 Mb
     0
RiemannRule9
RR9=Rie[-a,-b,-c,-d] Rie[-e,a,-gg,b]-
1/2 Rie[-p,-q,-c,-d] Rie[-e,-gg,p,q]//Index[gn]
 CPU Time=0.43 s Memory in use=2.655 Mb
                      m n
                 R         R
                  k l       m n i j
     0         - ------------------- +
      i j k l             2

          m   n
       R         R
        k   l     m n i j
RR9//Index[gn,SimplifyAllIndex[2]]
CPU Time=265.18 s Memory in use=3.66 Mb
     0
RiemannRule10
RR10=Ric[-a,-b] Rie[-c,-d,-e,a] Rie[b,c,d,e]+
1/2 Ric[-p,-q] Rie[-r,-s,-t,p]Rie[q,t,r,s]//Index[gn]
 CPU Time=0.39 s Memory in use=2.521 Mb
            j k l m         i
     R     R         R         +
      i j             k l m

              j k l m         i
       R     R         R
        i j             l m k
       -------------------------
                   2
RR10//Index[gn,SimplifyAllIndex[2]]
 CPU Time=16.7 s Memory in use=2.53 Mb
            i         j l k m
     R     R         R         -
      i j     k l m

                  i     k l j m
       R     R         R
        i j   k l   m
       -------------------------
                   2
RiemannRule11
RR11=Rie[-a,-b,-c,-d] Rie[-e,-f,a,b] Rie[c,e,d,f]-
1/2 Rie[-p,-q,-r,-s] Rie[-t,-u,p,q]Rie[r,s,t,u]//Index[gn]
 CPU Time=0.38 s Memory in use=2.521 Mb
                  k l m n       i j
     -(R         R         R        )
        i j k l             m n
     -------------------------------- +
                    2

                  k m l n       i j
       R         R         R
        i j k l             m n
RR11//Index[gn,SimplifyAllIndex[2]]
CPU Time=627.25 s Memory in use=2.997 Mb
     0
RR11//Index[gn,SimplifyAllIndex[2]]
 CPU Time=1.76 s Memory in use=2.992 Mb
     0
RiemannRule12
RR12=Rie[-a,-b,-c,-d] Rie[-e,a,-f,b] Rie[c,e,d,f]-
1/4 Rie[-p,-q,-r,-s] Rie[-t,-u,r,s]Rie[p,q,t,u]//Index[gn]
 CPU Time=0.39 s Memory in use=3.198 Mb
                k m l n     i   j
     R         R         R         -
      i j k l             m   n

                  i j m n       k l
       R         R         R
        i j k l             m n
       -----------------------------
                     4
RR12//Index[gn,SimplifyAllIndex[2]]
 CPU Time=1.65 s Memory in use=3.199 Mb
     0
RiemannRule13 (corrected from the original)
RR13=Rie[-a,-b,-c,-d] Rie[-e,a,-gg,b] Rie[c,d,e,gg]-
1/2 Rie[-p,-q,-r,-s] Rie[-t,-u,p,q]Rie[r,s,t,u]//Index[gn]
 CPU Time=0.38 s Memory in use=3.201 Mb
                k l m n     i   j
     R         R         R         -
      i j k l             m   n

                  k l m n       i j
       R         R         R
        i j k l             m n
       -----------------------------
                     2


RR13//Index[gn,SimplifyAllIndex[2]]
 CPU Time=1.59 s Memory in use=3.202 Mb

     0


RiemannRule14
RR14=Rie[-a,-b,-c,-d] Rie[-e,a,-gg,c] Rie[b,d,e,gg]-
1/4 Rie[-p,-q,r,s] Rie[-r,-s,t,u] Rie[p,q,-t,-u]//Index[gn]
 CPU Time=0.44 s Memory in use=3.204 Mb
            k l   i j           m n
     -(R         R         R        )
        i j           m n   k l
     -------------------------------- +
                    4

                  j l m n     i   k
       R         R         R
        i j k l             m   n
RR14//Index[gn,SimplifyAllIndex[2]]
 CPU Time=1.65 s Memory in use=3.204 Mb
     0
RiemannRule15
RR15=Rie[-a,-b,-c,-d] Rie[-e,a,-gg,c] Rie[b,gg,d,e]-
Rie[-p,-q,-r,-s] Rie[-t,p,-u,r] Rie[q,t,s,u]+
1/4 Rie[-p,-q,-r,-s] Rie[-t,-u,p,q]Rie[r,s,t,u]//Index[gn]
 CPU Time=0.6 s Memory in use=3.004 Mb
                  j m l n     i   k
     -(R         R         R        ) +
        i j k l             m   n

                  k l m n       i j
       R         R         R
        i j k l             m n
       ----------------------------- +
                     4

                  j m l n     i   k
       R         R         R
        i j k l             n   m
RR15//Index[gn,SimplifyAllIndex[2]]
 CPU Time=2.58 s Memory in use=3.004 Mb
     0
RiemannRule16
RR16=Ric[-a,-b,.;b]-1/2 R[.;-a] //Index[gn]
 CPU Time=0.55 s Memory in use=2.673 Mb
           R
            .;i         .;j
     0   - ----- + R
      i      2      i j
RR16//Index[gn,SimplifyAllIndex[2]]
 CPU Time=0.33 s Memory in use=2.674 Mb
     0
RiemannRule18
RR18=Ric[-a,-b,.;-c,.;b]-
1/2 R[.;-a,.;-c]- Ric[-p,-a]Ric[-c,p]+
Ric[-p,-q] Rie[-a,q,-c,p] //Index[gn]
 CPU Time=0.71 s Memory in use=3.658 Mb
             R
              .;i .;j       k
     0     - --------- - R     R     +
      i j        2        j     k i

                .;k             l   k
       R             + R     R
        i k .;j         k l   i   j
RR18//Index[gn,SimplifyAllIndex[2]]
 CPU Time=1.6 s Memory in use=3.659 Mb
     0
RiemannRule19
RR19=Ric[-a,-b,.;-c,.;a]-
1/2 R[.;-b,.;-c]-Ric[-p,-b] Ric[-c,p]+
        Ric[-p,-q] Rie[-b,q,-c,p]//Index[gn]
CPU Time=0.93 s Memory in use=2.682 Mb
             R
              .;i .;j       k
     0     - --------- - R     R     +
      i j        2        j     k i

                .;k             l   k
       R             + R     R
        k i .;j         k l   i   j
RR19//Index[gn,SimplifyAllIndex[2]]
 CPU Time=4.28 s Memory in use=2.683 Mb
     0
RiemannRule20
RR20=Rie[-a,-b,-c,-d,.;a]+Ric[-b,-c,.;-d]-Ric[-b,-d,.;-c]//Index[gn]
 CPU Time=0.5 s Memory in use=2.685 Mb
     0       + R         - R         +
      i j k     i j .;k     i k .;j

                .;l
       R
        l i j k
RR20//Index[gn,SimplifyAllIndex[2]]
 CPU Time=0.43 s Memory in use=2.685 Mb
     0
RiemannRule21
RR21=Rie[-a,-b,-c,-d,.;b]-Ric[-a,-c,.;-d]+Ric[-a,-d,.;-c]//Index[gn]
CPU Time=0.55 s Memory in use=2.687 Mb
     0       - R         + R         +
      i j k     i j .;k     i k .;j

                .;l
       R
        i l j k
RR21//Index[gn,SimplifyAllIndex[2]]
 CPU Time=0.44 s Memory in use=2.688 Mb
     0
RiemannRule22
RR22=Rie[-a,-b,-c,-d,.;c]+Ric[-a,-d,.;-b]-Ric[-b,-d,.;-a]//Index[gn]
 CPU Time=0.49 s Memory in use=2.69 Mb
     0       + R         - R         +
      i j k     i k .;j     j k .;i

                .;l
       R
        i j l k
RR22//Index[gn,SimplifyAllIndex[2]]
Creada la LlistaMonomis[gn,XX,3,2,1]
 CPU Time=2.69 s Memory in use=2.692 Mb
     0
RiemannRule23
RR23=Rie[-a,-b,-c,-d,.;d]-Ric[-a,-c,.;-b]+Ric[-b,-c,.;-a]//Index[gn]
 CPU Time=0.55 s Memory in use=2.694 Mb
     0       - R         + R         +
      i j k     i k .;j     j k .;i

                .;l
       R
        i j k l
RR23//Index[gn,SimplifyAllIndex[2]]
 CPU Time=2.09 s Memory in use=2.695 Mb
     0
RiemannRule24
RR24=R[.;-a,.;-b,.;a,.;b]-
1/2 R[.;-p] R[.;p]-
R[.;-p,.;p,.;-q,.;q]-
R[.;-p,.;-q] Ric[p,q]//Index[gn]
 CPU Time=0.99 s Memory in use=2.698 Mb
              .;i
     -(R     R    )
        .;i                .;i     .;j
     -------------- - R                 +
           2           .;i     .;j

                .;i .;j               i j
       R                 - R         R
        .;i .;j             .;i .;j
RR24//Index[gn,SimplifyAllIndex[2]]
CPU Time=6.7 s Memory in use=2.701 Mb
     0
RiemannRule25
RR25=Ric[-a,-b,.;-c,.;c,.;a,.;b]-
 1/2 R[.;-p]R[.;p]+
3 Ric[-p,-q,.;-r] Ric[p,q,.;r]-
4 Ric[-p,-q,.;-r] Ric[p,r,.;q]-
1/2 R[.;-p,.;p,.;-q,.;q]-
2 R[.;-p,.;-q] Ric[p,q]+
 Ric[-p,-q,.;-r,.;r] Ric[p,q]-
2 Ric[-p,-q] Ric[-r,p]Ric[q,r]+
2 Ric[-p,-q,.;-r,.;-s] Rie[p,r,q,s]+
2 Ric[-p,-q] Ric[-r,-s]Rie[p,r,q,s]//Index[gn]
 CPU Time=1.87 s Memory in use=3.667 Mb
              .;i          .;i     .;j
     -(R     R    )   R
        .;i            .;i     .;j
     -------------- - ----------------- -
           2                  2

                    i j
       2 R         R     -
          .;i .;j

                j k     i
       2 R     R     R     +
          i j         k

                    i j .;k
       3 R         R         -
          i j .;k

                    i k .;j
       4 R         R         +
          i j .;k

        i j           .;k
       R     R             +
              i j .;k

                .;k .;i .;j
       R                     +
        i j .;k

                      i k j l
       2 R     R     R         +
          i j   k l

                        i k j l
       2 R             R
          i j .;k .;l
RR25//Index[gn,SimplifyAllIndex[2]]
CPU Time=142.87 s Memory in use=3.813 Mb
     0
RiemannRule26
RR26=Rie[-a,-b,-c,-d,.;-e,.;e]-(
        Ric[-a,-c,.;-d,.;-b]-
        Ric[-a,-d,.;-c,.;-b]-
        Ric[-b,-c,.;-d,.;-a]+
        Ric[-b,-d,.;-c,.;-a]-
        Rie[-p,-q,-c,-d]Rie[-a,p,-b,q]+
        Ric[-p,-b]Rie[-a,p,-c,-d]-
        Rie[-p,-b,-q,-d]Rie[-a,p,-c,q]+
        Rie[-p,-b,-q,-c]Rie[-a,p,-d,q]-
        Ric[-p,-a]Rie[-b,p,-c,-d]+
        Rie[-p,-a,-q,-d]Rie[-b,p,-c,q]-
        Rie[-p,-a,-q,-c]Rie[-b,p,-d,q]-
        Rie[-p,-a,-q,-b]Rie[-c,-d,p,q])//Index[gn,Expand]
  CPU Time=2.31 s Memory in use=3.82 Mb
     0         - R             +
      i j k l     i k .;l .;j

       R             + R             -
        i l .;k .;j     j k .;l .;i

                                m
       R             - R     R         +
        j l .;k .;i     m j   i   k l

                m             m n
       R     R         + R         R         +
        m i   j   k l     k l       m i n j

          m   n
       R         R         -
        j   l     m i n k

          m   n
       R         R         -
        j   k     m i n l

          m   n
       R         R         +
        i   l     m j n k

          m   n
       R         R         +
        i   k     m j n l

          m   n                           .;m
       R         R         + R
        i   j     m n k l     i j k l .;m

RR26//Index[gn,SimplifyAllIndex[2]]
 CPU Time=5.76 s Memory in use=3.874 Mb
     0
RiemannRule34
RR34=Rie[a,f,b,c,.;-e] Rie[-a,-b,-c,-d]+
1/2 Rie[p,f,q,r,.;-e] Rie[-p,-d,-q,-r]//Index[gn]
 CPU Time=0.5 s Memory in use=3.876 Mb
                          l i m n
               R         R
      i         l k m n           .;j
     0       + ----------------------- +
        j k               2

                  l i m n
       R         R
        l m n k           .;j
RR34//Index[gn,SimplifyAllIndex[2]]
CPU Time=489.22 s Memory in use=5.352 Mb
     0

And now an example defining  some tensors and its symmetries explicitely.

 (
InputCoordinates[cx4,4];
InputSMetric[gn,cx4,"g",g];
InputSRiemann[gn,cx4,"R",Rie,Ric,R];
InputTensor[{L},cx4,{1,1,1}];
InputTensor[{V},cx4,{1}];
InputSymmetries[L[i,j,k],{i,k}[2]];
InputSymmetries[L[i,j,k,.;m],{i,j}[2],
        Cyclic[j,k,m][2]];
InputIndex[{a,b,c,d,e,m,n}]);
Dimension[cx4]=4
CPU Time=0.55 s Memory in use=2.525 Mb

3/2 L[i,j,k] Rie[-i,-j,q,p] V[-k]//Index[gn]
 CPU Time=0.22 s Memory in use=2.532 Mb
                c d e           a b
             3 L       V   R
      a b               e   c d
     0     + -----------------------
                        2
%//Index[gn,SimplifyAllIndex[2]]
CPU Time=462.53 s Memory in use=2.987 Mb
                b       d   c a
             3 L       V   R
      a b         c d
     0     - ------------------- +
                      4

            b     d   c a
       3 L       V   R
          c   d
       ------------------- +
                4

          a       d   c b
       3 L       V   R
            c d
       ------------------- -
                4

            a     d   c b
       3 L       V   R
          c   d
       ------------------- +
                4

            a b       c d         b a       c d
       3 L       V   R       3 L       V   R
          c       d             c       d
       ------------------- - -------------------
               4                     4
Note that if Ricci=0 then this is zero which is not obviously at all from the original expression

Bianchi II hard force demonstration

This section is devoted to demonstrate via hard calculus the Bianchi II relations of the Riemann tensor . This means that we will define a Riemann tensor in terms of Christoffel and metrics and then construct the Bianchi II relation. The expression will we a very large one but TTC must find that in fact it is zero (perhaps it would take some time to do the calculus...).
We use SymmApply to do this calculations because there are partial derivatives and SimplifyAllIndex[2] is not adapted to work with partial derivatives because of the fall of tensor character.
We initiate a new Mathematica session and start reading the files of the programs:

<<path/ttc.m

 ----------------------------------------
|TTC: Tools of Tensor Calculus 4.3.1|
| A.Balfagon,P.Castellvi and X.Jaen |
| http://baldufa.upc.edu/ttc |
| e-mail:Xavier.Jaen@upc.edu |
| version: june, 1, 2005 |
----------------------------------------
| TTC works correctly with |
| Cell menu options: |
| Default Input FormatType=InputForm |
| Default Output FormatType=OutputForm |
----------------------------------------
| Session started on |
| June, 5 , 2005 |
| at 17 h 50 min 6.981 s |
----------------------------------------

InputCoordinates[x,4]
Dimension[x]=4
 CPU Time=0. s Memory in use=2.458 Mb

InputSMetric[gx,x,"g",g]
 CPU Time=0.05 s Memory in use=2.466 Mb
     {g}

InputSChristoffelTensor[gx,x,"G",G]
 CPU Time=0.06 s Memory in use=2.473 Mb
     {g, G}

GtoM=IndexUpdate[G,":>",1/2 g[i,-s] g[j,-r]g[s,r,.,k]+
                            1/2 g[i,-s] g[k,-r]g[s,r,.,j]-
                           1/2  g[j,-s] g[k,-r]g[s,r,.,i]];
 CPU Time=7.68 s Memory in use=2.489 Mb

InputTensor[R,x,{1,-1,-1,-1}]
 CPU Time=0. s Memory in use=2.491 Mb
     {g, G, R}

InputIndex[{i,j,k,l,m,n,o,p}];
CPU Time=0. s Memory in use=2.491 Mb

RtoG=IndexUpdate[R,":>",0[i,j,k,l]+
        g[i,-m]g[j,n] g[k,s] G[m,-n,-s,.,l]-
        g[i,-m]g[j,n] g[l,s]G[m,-n,-s,.,k]+
        G[-h,j,k] G[i,l,h]- G[-h,j,l] G[i,k,h]];

 
 CPU Time=0.27 s Memory in use=2.499 Mb

 R[i,-j,-k,-l,.;-m]+R[i,-j,-m,-k,.;-l]+R[i,-j,-l,-m,.;-k]//Index[gx]
 CPU Time=0.5 s Memory in use=2.504 Mb
      i             i
     0           + R             +
        j k l m       j k l .;m

        i               i
       R             + R
          j l m .;k       j m k .;l

%//Index[gx,CovariantToPartial]
 CPU Time=1.59 s Memory in use=2.516 Mb
      i             i
     0           + R             +
        j k l m       j k l .,m

        i               i
       R             + R             +
          j l m .,k       j m k .,l

                  i   n               i   n
       R         G       + R         G       +
        n j l m     k       n j m k     l

                  i   n     i n
       R         G       - R         G       -
        n j k l     m           l m   n k j

        i   n               i     n
       R         G       - R         G       -
          j   m   n k l       j l     n k m

        i n                 i     n
       R         G       - R         G       -
            m k   n l j       j m     n l k

        i   n               i n
       R         G       - R         G       -
          j   k   n l m         k l   n m j

        i   n               i     n
       R         G       - R         G
          j   l   n m k       j k     n m l

%//Index[gx,TensorRules[RtoG]]

 CPU Time=12.8 s Memory in use=2.537 Mb
      i             i   n
     0           + G
        j k l m       m

              o                 o
        (G       G       - G       G       +
          n l     o j k     n k     o j l

           p               p1     p2
          G             g      g      g     -
             p1 p2 .,l   j      k      n p

           p               p1     p2
          G             g      g      g    ) +
             p1 p2 .,k   j      l      n p

        i   n          o
       G       (-(G       G      ) +
          l        n m     o j k

               o
          G       G       -
           n k     o j m

           p               p1     p2
          G             g      g      g     +
             p1 p2 .,m   j      k      n p

           p               p1     p2
          G             g      g      g    ) +
             p1 p2 .,k   j      m      n p

        i   n        o
       G       (G       G       -
          k      n m     o j l

               o
          G       G       +
           n l     o j m

           p               p1     p2
          G             g      g      g     -
             p1 p2 .,m   j      l      n p

           p               p1     p2
          G             g      g      g    ) -
             p1 p2 .,l   j      m      n p

                 i   o     n
       G       (G       G       -
        n m j      l     o   k

           i   o     n
          G       G       +
             k     o   l

           p             i       p2   n p1
          G             g     g      g      -
             p1 p2 .,l     p   k

           p             i       p2   n p1
          G             g     g      g     ) -
             p1 p2 .,k     p   l

                   i   o     n
       G       (-(G       G      ) +
        n l j        m     o   k

           i   o     n
          G       G       -
             k     o   m

           p             i       p2   n p1
          G             g     g      g      +
             p1 p2 .,m     p   k

           p             i       p2   n p1
          G             g     g      g     ) -
             p1 p2 .,k     p   m

                 i   o     n
       G       (G       G       -
        n k j      m     o   l

           i   o     n
          G       G       +
             l     o   m

           p             i       p2   n p1
          G             g     g      g      -
             p1 p2 .,m     p   l

           p             i       p2   n p1
          G             g     g      g     ) -
             p1 p2 .,l     p   m

                 i n o
       G       (G       G       -
        n m l            o j k

           i   o       n
          G       G       +
             k     o j

           p       .,n   i       p1     p2
          G             g     g      g      -
             p1 p2         p   j      k

           p             i       p1   n p2
          G             g     g      g     ) -
             p1 p2 .,k     p   j

                   i n o
       G       (-(G       G      ) +
        n l m              o j k

           i   o       n
          G       G       -
             k     o j

           p       .,n   i       p1     p2
          G             g     g      g      +
             p1 p2         p   j      k

           p             i       p1   n p2
          G             g     g      g     ) -
             p1 p2 .,k     p   j

                 i n o
       G       (G       G       -
        n k m            o j l

           i   o       n
          G       G       +
             l     o j

           p       .,n   i       p1     p2
          G             g     g      g      -
             p1 p2         p   j      l

           p             i       p1   n p2
          G             g     g      g     ) -
             p1 p2 .,l     p   j

                   i n o
       G       (-(G       G      ) +
        n m k              o j l

           i   o       n
          G       G       -
             l     o j

           p       .,n   i       p1     p2
          G             g     g      g      +
             p1 p2         p   j      l

           p             i       p1   n p2
          G             g     g      g     ) -
             p1 p2 .,l     p   j

                 i n o
       G       (G       G       -
        n l k            o j m

           i   o       n
          G       G       +
             m     o j

           p       .,n   i       p1     p2
          G             g     g      g      -
             p1 p2         p   j      m

           p             i       p1   n p2
          G             g     g      g     ) -
             p1 p2 .,m     p   j

                   i n o
       G       (-(G       G      ) +
        n k l              o j m

           i   o       n
          G       G       -
             m     o j

           p       .,n   i       p1     p2
          G             g     g      g      +
             p1 p2         p   j      m

           p             i       p1   n p2
          G             g     g      g     ) +
             p1 p2 .,m     p   j

         i   n             i   n
       (G       G       - G       G       +
           l     n j k       k     n j l

          o            i       p     p1
         G            g     g     g      -
            p p1 .,l     o   j     k

          o            i       p     p1
         G            g     g     g     )    \
            p p1 .,k     o   j     l     .,m

              i   n
        + (-(G       G      ) +
                m     n j k

          i   n
         G       G       -
            k     n j m

          o            i       p     p1
         G            g     g     g      +
            p p1 .,m     o   j     k

          o            i       p     p1
         G            g     g     g     )    \
            p p1 .,k     o   j     m     .,l

            i   n             i   n
        + (G       G       - G       G       +
              m     n j l       l     n j m

          o            i       p     p1
         G           g     g     g      -
            p p1 .,m     o   j     l

          o            i       p     p1
         G            g     g     g     )
            p p1 .,l     o   j     m     .,k

%//Index[gx,SimplifyAllIndex[SymmApply]]
 CPU Time=292.15 s Memory in use=2.561 Mb
     0
It is not necessary to convert Chistoffel symbols to metric (GtoM) . Only symmetry properties of Christoffel's are necessary.
 
 

This page is maintained by XavierJaén and Albert Balfagón.