### The Maxima on-line user's manual

Algebra Calculator

#### Defcon

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 `imetric:g`, then `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 `defcon`.

```(%o1)                                true
(%i2) ```

? defcon;

Calculate

? defcon;

Calculate