关系规范代数范畴(Ω,R,E)-alg中自由对象的存在性(英文)

THE EXISTENCE OF FREE OBJECTS IN THE CATEGORY (Ω, R, E)-ALG OF RELATIONAL SPECIFICATION ALGEBRAS

本文给出（Ω，R）－代数直积的概念，证明范畴（Ω，R，E）－alg关于子代数、直积和同态像运算封闭。从而得到该范畴中自由对象的存在性定理。最后讨论关系规范代数约化的概念及其性质。

In this paper we define the direct product of (Q, R, E) -algebras, and prove thatthe category (O,R,E) -alg is closed under the operations of taking subalgebras, directproducts and homomorphic images. Then the existence theorem of free objects in this categoryis obtained. Finally, we discuss the concept of reduction and its properties