Hello everyone,

I was thinking of Implementing *Permutation group triple product property* 
as suggested by *S.Y. Lee* here (https://github.com/sympy/sympy/issues/18525
). 
You can see more about it using these two links:
1.)https://en.wikipedia.org/wiki/Triple_product_property
2.)https://arxiv.org/pdf/1104.5097.pdf

*Permutation group triple product property: *(Reference Wikipedia)

Let {\displaystyle G}[image: G] be a non-trivial group. Three nonempty 
subsets {\displaystyle S,T,U\subset G}[image: {\displaystyle S,T,U\subset 
G}] are said to have the *triple product property* in {\displaystyle G}[image: 
G] if for all elements {\displaystyle s,s'\in S}[image: {\displaystyle 
s,s'\in S}], {\displaystyle t,t'\in T}[image: {\displaystyle t,t'\in T}], 
{\displaystyle 
u,u'\in U}[image: {\displaystyle u,u'\in U}] it is the case that
{\displaystyle s's^{-1}t't^{-1}u'u^{-1}=1\Rightarrow s'=s,t'=t,u'=u}[image: 
{\displaystyle s's^{-1}t't^{-1}u'u^{-1}=1\Rightarrow s'=s,t'=t,u'=u}]

where {\displaystyle 1}[image: 1] is the identity of {\displaystyle G}[image: 
G].

So there is one algorithm mentioned in here (2.)
https://arxiv.org/pdf/1104.5097.pdf Which is given below.

Here *S, T, U *are *subgroups.*

So I am expriencing some problem in implementation of this algorithm.

   - As we can see intersection is used here and till now sympy does not 
   contain any function for *intersection of two groups*.
   - We can also see that here we are interested in finding whether the 
   intersection of two subgroups is *trivial* or not so maybe se can avoid 
   calculating intersection for of two groups.
   - I was also thinking of using property "T*wo Normal Subgroups 
   Intersecting Trivially Commute Each Other*" (
   
https://yutsumura.com/two-normal-subgroups-intersecting-trivially-commute-each-other/)
 
   but this will work only for *Normal groups*.

Can we have discussion that what should be the best approach here?

def test(S, T, U):
    if( T ∩ U = 1 ) then
        if( S ∩ T · U = 1 ) then
            return true;
    fi; fi;
    return false;

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