Function: defcon (<tensor_1>)
Function: defcon (<tensor_1>, <tensor_2>, <tensor_3>) gives <tensor_1> the property that the contraction of a product of <tensor_1> and <tensor_2> results in <tensor_3> with the appropriate indices. If only one argument, <tensor_1>, is given, then the contraction of the product of <tensor_1> with any indexed object having the appropriate indices (say
my_tensor) will yield an indexed object with that name, i.e.
my_tensor, and with a new set of indices reflecting the contractions performed. For example, if
defcon(g) will implement the raising and lowering of indices through contraction with the metric tensor. More than one
defcon can be given for the same indexed object; the latest one given which applies in a particular contraction will be used.
contractions is a list of those indexed objects which have been given contraction properties with
(%o1) true (%i2)