I noticed the following error description in the document of NullSpace:
The null space is less than the dimension of the matrix, so it is not invertible:
![enter image description here](https://community.wolfram.com//c/portal/getImageAttachment?filename=Selection_287.png&userId=2470387)
Obviously, the correct equivalent conditions should be described as follows:
- The null space of A is {0}.
- The dimension of the null space of A is 0.
Regards,
Zhao