replacement of a tractor is an influential factor affecting timely farm operation. the accurate prediction of repair and maintenance costs is essential to selection of a replacement model. this study used empirical data for 60 two-wheel drive (2wd) tractors from astan ghods-e razavi agroindustry. the types and numbers of tractors used were the massey ferguson 285 (17), fiat (10), john deere 314...

We prove the exponential growth of product replacement graphs for a large class of groups. Much of our effort is dedicated to the study of product replacement graphs of Grigorchuk groups, where the problem is most difficult.

;its minimal faithful permutation and matrix representation degrees are respectively 97 239 461 142 009 186 000 and 196 882. This makes it far harder to work with than the 25 smaller sporadics. In Section 3, we describe techniques which allow limited computation in the Monster. In Section 4, we describe our experiments to assess the effectiveness of combining these techniques with a suitable ve...

The product replacement algorithm is a practical algorithm to construct random elements of a finite group G. It can be described as a random walk on a graph Γk(G) whose vertices are the generating ktuples of G (for a fixed k). We show that if G = PSL(2, q) or PGL(2, q), where q is a prime power, then Γk(G) is connected for any k ≥ 4. This generalizes former results obtained by Gilman and Evans.

We present a parallel algorithm for nding triconnected components on a CRCW PRAM. The time complexity of our algorithm is O(logn) and the processor-time product is O((m + n) log logn) where n is the number of vertices, and m is the number of edges of the input graph. Our algorithm, like other parallel algorithms for this problem, is based on open ear decomposition but it employs a new technique...

Let G be a group with Kazhdan’s property (T), and let S be a transitive generating set (there exists a group H ⊂ Aut(G) which acts transitively on S.) In this paper we relate two definitions of the Kazhdan constant and the eigenvalue gap in this case. Applications to various random walks on groups, and the product replacement random algorithm, are also presented.

Deterministic replay of parallel execution and communication operations is required both by HPC debuggers and resilience mechanisms. Despite its potential performance advantages, the inherent nondeterminism present in one-sided communication makes replaying difficult. The essential problem is that the readers of updated shared data do not have any information on which remote threads produced th...

Data Grid provides sharing services for very large data around the world. Data replication is one of the most effective approaches to reduce access latency and response time. In addition to the benefits, replication has costs such as storage and bandwidth consumption, especially when storage space is low and limited. Therefore,  the data replacement should be done wisely. In this p...