linear algebra - prove that every spanning set can be trimmed to a basis
in linear algebra, finally add stenitz lemma, dimension theorem and the definition of dimension for FDVS
prove that image of basis is the basis of the image
add a fix for 'image of basis is basis of image' in the case where some basis elements get mapped to zero
initial commit on matroid notes
complete proof of nonnegativity of nullity. prove nullity is monotonic and subsets of ind. sets are ind. (matroids)