Answer 1aWe impose a constraint to have meaningful results, since every entry in x represents a travel time on a link of the network. bIn general, the matrix A may not be full column rank, therefore the closedform solution cannot be applied. We remedy the normal leastsquare equation by applying the socalled regularized least squares. We solve the following problem instead: Observe that the two norms are independent, given x. cNumerical Implementation
