Talk:Support vector machine/Archives/2014

Does the solution lie at a saddle point?
The "Primal form" section says that "we look for a saddle point". Is this correct? What is thefunction that this is a saddle point of? Is it a saddle point of $$f(w,b)=\max_{\alpha}\frac{1}{2}||w||^2+\sum_i\alpha_i(y_i(w_i x_i-b)-1)$$? It doesn't seem clear that this is even differentiable. The objective function (the norm squared of (w,b)) is positive semi-definite, so I don't think it has any saddle points.Vinzklorthos (talk) 01:37, 7 February 2014 (UTC)

Contradiction in primal form?
IMHO, the section on the determination of $$b$$ at the end of the primal form section is unclear and seems contradictory. More precisely, the statement "the b depends on y_i and x_i" does not seem to follow from anything previously said. On the contrary, the previous statement "From this one can derive that the support vectors also satisfy ..." refers to a single value of $$w$$ and $$b$$ for which the given equations hold. Veryltdbeard (talk) 11:11, 27 October 2014 (UTC)