We characterize the complexity of some natural and important
problems in linear algebra. In particular, we identify natural
complexity classes for which the problems of (a) determining if a
system of linear equations is feasible and (b) computing the rank of
an integer matrix, ... more >>>

The rank of a matrix has been used a number of times to prove lower
bounds on various types of complexity. In particular it has been used
for the size of monotone formulas and monotone span programs. In most
cases that this approach was used, there is not a single ... more >>>

Monotone span programs are a linear-algebraic model of computation which were introduced by Karchmer and Wigderson in 1993. They are known to be equivalent to linear secret sharing schemes, and have various applications in complexity theory and cryptography. Lower bounds for monotone span programs have been difficult to obtain because ... more >>>