Both Vandermonde and Cauchy matrices with $n$ rows and $k$ ($n \geq k$) columns have the property that any $k$ rows are linearly independent (assuming the coefficient are independent). It seems to me that if you concatenates the rows of the identity matrix $I_k$ then the $k$-linear independence is preserved in the resulting ($k+n$ x $k$) matrix.
I want to use this claim in a paper and I want to know if there is already a formal work that I can cite to back up my (supposed true) claim. Otherwise I will do it in the annex section and post it here too.
thanks
