Angle Bracket. An angle bracket is the combination of a bra and ket (bra+ket = bracket) which represents the inner product of two functions or vectors (or 1-forms), in a function space, or. in a vector space. Here, represents the adjoint. The expression is also commonly used to denote the expectation value of a variable .
Definition: In the ancient Peloponnese, Helots were area residents exploited, like the proverbial serf, by the ancient Spartans. The origins of the helots are disputed. One theory is that when the Spartans realized they needed more arable land they looked to the southwest to the more fertile soil of Messenia. The helots were conquered Laconians whom the Spartans made subservient.
Since the helot population was not technically chattel, their population was reliant on native birth rates, as opposed to prisoners of war or purchased slaves. Helots were encouraged by the Spartans to impose a eugenics doctrine similar to that which they, themselves, practiced.