AllContractions[expr] returns a sorted list of all possible full contractions of expr over its free indices. 
AllContractions[expr, frees] returns all possible contractions of expr that have frees as free indices. 
AllContractions[expr, frees, sym] returns all possible contractions of expr with the symmetry sym imposed on the free indices frees. 
Verbose  False  display information while computing  
Parallelization  True  whether or not to distribute the computation over all available kernels  
SymmetrizeMethod  ImposeSymmetry  how to symmetrize the free indices  
UncontractedIndices  None  how many indices should not be contracted  
FreeMetrics  All  contractions with this many of free metrics will be included  
AuxiliaryTensor  Default  name of the auxiliary tensor used internally 
ImposeSymmetry  explicity symmetrize the free indices  
ImposeSym  implicitly symmetrize the free indices  
None  do not symmetrize the free indices, but instead keep the auxiliary tensor 
None  contract over all indices (i.e. all indices of the input expression and additionally specified free indices)  
n  do not contract n of the indices, where is an integer between 0 and the total number of indices. 
All  contractions with any number of free metrics will be included  
None  only contractions without free metrics will be included  
n  only contractions with 0 to n number of free metrics will be included  
{m,n}  only contractions with m to n number of free metrics will be included 
Default  automatically generate a name for the internally used auxiliary tensor  
head  the symbol head will be used as the auxiliary tensor 
Typing all the indices can become cumbersome, so instead we can use the pseudo indexfree notation:

Options (4) 