Each such morphism is necessarily an order-embedding. In this section we show that [E.sub.[less than or equal to]]-injective objects in the category [PoSgr.sub.[less than or equal to]] are precisely the quantales.
The mapping [eta]: (S, *, [less than or equal to]) [right arrow] (P(S), *, [subset or equal to]), given by [eta](a) = a[down arrow] for each a [member of] S, is clearly an order-embedding of the poset (S, [less than or equal to]) into the poset (P(S), [subset or equal to]).
This means that [eta] is both monotone and an order-embedding. If now [eta]([a.sub.1]) [omicron] ...