let $r$ be a ring‎, ‎and let $n‎, ‎d$ be non-negative integers‎. ‎a right $r$-module $m$ is called $(n‎, ‎d)$-projective if $ext^{d+1}_r(m‎, ‎a)=0$ for every $n$-copresented right $r$-module $a$‎. ‎$r$ is called right $n$-cocoherent if every $n$-copresented right $r$-module is $(n+1)$-coprese-nted‎, ‎it is called a right co-$(n,d)$-ring if every right $r$-module is $(n‎, ‎d)$-projective‎. ‎$r$ ...

The main results: A ring R is CN if and only if for any x ∈ N(R) and y ∈ R, ((1+x)y)n+k = (1+x)n+kyn+k, where n is a fixed positive integer and k = 0, 1, 2; (2) Let R be a CN ring and n ≥ 1. If for any x, y ∈ R\N(R), (xy)n+k = xn+kyn+k, where k = 0, 1, 2, then R is commutative; (3) Let R be a ring and n ≥ 1. If for any x ∈ R\N(R) and y ∈ R, (xy)k = xkyk, k = n, n + 1, n + 2, then R is commutati...

a polynomial   1 2 ( , , , ) n f x x x is called multilinear if it is homogeneous and linear in every one of its variables. in the present paper our objective is to prove the following result: let   r be a prime k-algebra over a commutative ring   k with unity and let 1 2 ( , , , ) n f x x x be a multilinear polynomial over k. suppose that   d is a nonzero derivation on r such that ...

Orbital magnetism in an integrable model of a multichannel ring with long-ranged electron-electron interactions is investigated. In a noninteracting multichannel system, the response to an external magnetic flux is the sum of many diamagnetic and paramagnetic contributions, but we find that for sufficiently strong correlations, the contributions of all channels add constructively, leading to a ...

Let R be an Abelian exchange ring. We prove the following results: 1. RZ2 and RS3 are clean rings. 2. If G is a group of prime order p and p is in the Jacobson radical of R, then RG is clean. 3. If identity in R is a sum of two units and G is a locally finite group, then every element in RG is a sum of two units. 4. For any locally finite group G, RG has stable range one. All rings in this note...

We introduce the notion of clean ideal, which is a natural generalization of clean rings. It is shown that every matrix ideal over a clean ideal of a ring is clean. Also we prove that every ideal having stable range one of a regular ring is clean. These generalize the corresponding results for clean rings. 1. Introduction. Let R be a unital ring. We say that R is a clean ring in case every elem...

An element $a$ in a ring $R$ is very clean in case there exists‎ ‎an idempotent $ein R$ such that $ae = ea$ and either $a‎- ‎e$ or $a‎ + ‎e$ is invertible‎. ‎An element $a$ in a ring $R$ is very $J$-clean‎ ‎provided that there exists an idempotent $ein R$ such that $ae =‎ ‎ea$ and either $a-ein J(R)$ or $a‎ + ‎ein J(R)$‎. ‎Let $R$ be a‎ ‎local ring‎, ‎and let $sin C(R)$‎. ‎We prove that $Ain K_...

Let P be a commutative Noetherian ring, ???? an ideal of which is generated by regular sequence length four, f element P, and P¯ the hypersurface ring P?(f). Assume that ????:f grade four Gorenstein P. We give resolution N P¯?????P¯ free P¯-modules. The built from differential graded algebra P?(????:f) P-modules, together with one homotopy map. In particular, we explicit form for matrix factori...

A commutative ring A is said to be clean if every element of A can be written as a sum of a unit and an idempotent. This definition dates back to 1977 where it was introduced by W. K. Nicholson [7]. In 2002, V. P. Camillo and D. D. Anderson [1] investigated commutative clean rings and obtained several important results. In [4] Han and Nicholson show that if A is a semiperfect ring, then A[Z2] i...

In this paper we characterize the radical of an arbitrary‎ ‎submodule $N$ of a finitely generated free module $F$ over a‎ ‎commutatitve ring $R$ with identity‎. ‎Also we study submodules of‎ ‎$F$ which satisfy the radical formula‎. ‎Finally we derive‎ ‎necessary and sufficient conditions for $R$ to be a‎ ‎Pr$ddot{mbox{u}}$fer domain‎, ‎in terms of the radical of a‎ ‎cyclic submodule in $Rbigopl...