• فهرس المقالات connected graph

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        1 - طیف رده ای از گراف های به دست آمده از گراف های گرسمن
        رویا کوگانی سید مرتضی میرافضل
        فرض کنید n و k اعداد صحیح مثبتی باشند به طوری که n ≥ 3و k < n/2 ، همچنین q توانی از عدد اولی مانند p و F_q یک میدان متناهی از مرتبه q باشد. V(q,n) را یک فضای برداری با بعد n روی F_q در نظر بگیرید، گراف S( q , n , k) را گرافی با مجموعه رئوس V = V_k ∪ V_(k+1) که أکثر
        فرض کنید n و k اعداد صحیح مثبتی باشند به طوری که n ≥ 3و k < n/2 ، همچنین q توانی از عدد اولی مانند p و F_q یک میدان متناهی از مرتبه q باشد. V(q,n) را یک فضای برداری با بعد n روی F_q در نظر بگیرید، گراف S( q , n , k) را گرافی با مجموعه رئوس V = V_k ∪ V_(k+1) که V _ k و V _ (k+1) به ترتیب خانواده همه زیرفضاهای با بعد k و k+1 از V( q,n ) می باشند، تعریف می کنیم که در آن هر دو رأس مانند v و w مجاورند هرگاه زیرفضایی از w یا w زیرفضایی از v باشد. واضح است که گراف S ( q , n , k) یک گراف دوبخشی است. در این مقاله به بررسی برخی از ویژگی های این گراف می-پردازیم، به ویژه طیف گراف S(q,n,k) را مشخص می کنیم. تفاصيل المقالة
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        2 - Study on the New Graph Constructed by a Commutative Ring
        زهرا یاراحمدی
        Let R be a commutative ring and G(R) be a graph with vertices as proper andnon-trivial ideals of R. Two distinct vertices I and J are said to be adjacentif and only if I + J = R. In this paper we study a graph constructed froma subgraph G(R)\Δ(R) of G(R) which con أکثر
        Let R be a commutative ring and G(R) be a graph with vertices as proper andnon-trivial ideals of R. Two distinct vertices I and J are said to be adjacentif and only if I + J = R. In this paper we study a graph constructed froma subgraph G(R)\Δ(R) of G(R) which consists of all ideals I of R such thatI Δ J(R), where J(R) denotes the Jacobson radical of R. In this paper westudy about the relation between the number of maximal ideal of R and thenumber of partite of graph G(R)\4(R). Also we study on the structure of ringR by some properties of vertices of subgraph G(R)\4(R). In another section,it is shown that under some conditions on the G(R), the ring R is Noetherianor Artinian. Finally we characterize clean rings and then study on diameterof this constructed graph. تفاصيل المقالة
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        3 - On the commuting graph of some non-commutative rings with unity
        F. Ramezani E. Vatandoost
        ‎‎Let $R$ be a non-commutative ring with unity‎. ‎The commuting graph‎ of $R$ denoted by $\Gamma(R)$‎, ‎is a graph with a vertex set‎‎$R\setminus Z(R)$ and two vertices $a$ and $b$ are adjacent if and only if‎$ab=ba$‎. ‎In أکثر
        ‎‎Let $R$ be a non-commutative ring with unity‎. ‎The commuting graph‎ of $R$ denoted by $\Gamma(R)$‎, ‎is a graph with a vertex set‎‎$R\setminus Z(R)$ and two vertices $a$ and $b$ are adjacent if and only if‎$ab=ba$‎. ‎In this paper‎, ‎we investigate non-commutative rings with unity of order $p^n$ where $p$ is prime and $n \in \lbrace 4,5 \rbrace$‎. It is shown that‎, ‎$\Gamma(R)$ is the disjoint union of complete graphs‎. Finally‎, ‎we prove that there are exactly five commuting‎‎graphs of non-commutative rings with unity up to twenty vertices and they are $3K_2,3K_4,7K_2‎, ‎K_2 \cup 2K_6$ and $4K_2 \cup K_6$‎. تفاصيل المقالة
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        4 - On the commuting graph of non-commutative rings of order $p^nq$
        E. Vatandoost F. Ramezani A. Bahraini
        Let $R$ be a non-commutative ring with unity. The commuting graph of $R$ denotedby $\Gamma(R)$, is a graph with vertex set $R\Z(R)$ and two vertices $a$ and $b$ are adjacent iff $ab=ba$.In this paper, we consider the commuting graph of non-commutative rings of order pq أکثر
        Let $R$ be a non-commutative ring with unity. The commuting graph of $R$ denotedby $\Gamma(R)$, is a graph with vertex set $R\Z(R)$ and two vertices $a$ and $b$ are adjacent iff $ab=ba$.In this paper, we consider the commuting graph of non-commutative rings of order pq and $p^2q$with Z(R) = 0 and non-commutative rings with unity of order $p^3q$. It is proved that $C_R(a)$is a commutative ring for every $0\neq a \in R\Z(R)$. Also it is shown that if $a,b\in R\Z(R)$and $ab\neq ba$, then $C_R(a)\cap C_R(b)= Z(R)$. We show that the commuting graph $\Gamma(R)$ is thedisjoint union of $k$ copies of the complete graph and so is not a connected graph. تفاصيل المقالة