The Upper Radical Determined by the Class of all J-Semisimple Subdirectly Irreducible Rings

F.A.Szasz has put forward the open problem 55 in [1]: Let K be the class of all subdirectly irreducible rings, whose Jacobson radical is (0). Examine the upper radical determined by the class K. In this paper, the problem has been examined. (1) It has been proved that the upper radical R determined by the class K is a special radical,which lies between Jacobson radical and Brown-McCoy radical. (2) It has been given some necessary and sufficient condition of ring A to be an R-radical ring.

DE MORGAN ALGEBRAS WITH DOUBLE DEMI-PSEUDOCOMPLEMENTATION

The variety ddpM of de Morgan algebras with double demi-pseudocomplementation consists of those algebras （L; ∧ , ∨ , , , ＋ , 0, 1） of type （2, 2, 1, 1, 1, 0, 0） where （L; ∧ , ∨ , , 0, 1） is a de Morgan algebra, （L; ∧ , ∨ , , ＋ , 0, 1） is a double demi-p-lattice and the operations x → x , x → x and x → x ＋ are linked by the identities x = x , x ＋ = x ＋ and x ＋ = x ＋ . In this paper, we characterize congruences on a ddpM-algebra, and give a description of the subdirectly irreducible algebras.

Congruences on Balanced Pseudocomplemented Ockham Algebras

The variety bpO consists of those algebras （L; ∧,∨, f,＊ ） of type 〈2,2,1, 1,0,0〉 where （L; ∧,∨, f, 0, 1） is an Ockham algebra, （L; ∧,∨, ＊, 0, 1） is a p-algebra, and the operations x → f（x） and x → x^＊ satisfy the identities f（x^＊） = x^＊＊ and [f（x）]^＊ = f^2（x）. In this note, we show that the compact congruences on a bpO-algebra form a dual Stone lattice. Using this, we characterize the algebras in which every principal congruence is complemented. We also give a description of congruence coherent bpO-algebras.

Commuting double Ockham algebras

In this paper,we study a certain class of double Ockham algebras (L;∧,∨,f,k,0,1), namely the bounded distributive lattices (L;∧,∨,0,1) endowed with a commuting pair of unary op- erations f and k,both of which are dual endomorphisms.We characterize the subdirectly irreducible members,and also consider the special case when both (L;f) and (L;k) are de Morgan algebras.We show via Priestley duality that there are precisely nine non-isomorphic subdirectly irreducible members, all of which are simple.

Closure Extended Pseudocomplemented MS-Algebras

The variety CPMS of closure extended pseudocomplemented MS-algebras consists of the algebras(L;∧,∨,°,*,+,0,1)of type(2,2,1,1,1,0,0),where(L;∧,∨,°,*,+,0,1)is a pseudocomplemented MS-algebra,+is a lattice endomorphism on L with x≤x^(+)=x^(++)and the operations x→x°,x→x^(*)and x→x^(+)are linked by the identities x^(+*)=x^(*+)and x^(+)°=x°^(+).In this paper,we characterize congruences on a CPMS-algebra,and show that there are precisely eight non-isomorphic subdirectly irreducible nontrivial algebras in the class of these algebras and give a complete description of them.

Graded Antisimple Primitive Radical

We introduce the graded version of the antisimple primitive radical SJ, the graded an- tisimple prinfitive radical SJ_G. We show that SJ_G=SJ_(ref)=SJ^G when |G|<∞. where SJ_(ref) denotes the reflected antisimple primitive radical and SJ^G denotes the restricted antisimple primitive radical. Furthermore, we discuss the graded supplementing radical of SJ^G.

Axioms in the Variety of eO-Algebras

The variety eO of extended Ockham algebras consists of those algebras （L; ∧, ∨, f, k, 0, 1） such that （L; ∧, ∨, 0, 1） is a bounded distributive lattice together with a dual endomorphism f on L and an endomorphism k on L such that fk = kf. In this paper we extend Urquhart＇s theorem to eO-algebras and we are in particular concerned with the subclass e2M of eO-algebras in which f^2 = id and k^2 = id. We show that there are 19 non-equivalent axioms in e2M and then order them by implication.