Beta-Dollar Neutral Portfolio Construction

Does any one can explain what is the Beta-Dollar Neutral Portfolio Construction? Especially the interpretation of the maximization problem below in terms of Beta-Dollar Neutral Portfolio Construction? what is the interpretation of the solution, x, to this problem? or introduce some reference to study. min (x − y)'(x − y) s.t. x’1 = 0 , x’b = 0

Note:To explore beta-dollar neutrality further, suppose that the vector y consists of long-short portfolio weights chosen with your favorite method (e.g., a decile sort), without regard to beta- or dollar neutrality.Specifically, y is the portfolio at time t and it varies over time, but we just write y (rather than yt) for simplicity. 1 is vector of one and b is beta.

I need to know how the maximization problem and what is the interpretation of it.

Where did you get this question?

Certainly not from the Level III CFA curriculum.