Self-converse Large Sets of Pure Mendelsohn Triple Systems

A Mendelsohn triple system of order v （MTS（v）） is a pair （X,B） where X is a v-set and 5g is a collection of cyclic triples on X such that every ordered pair of X belongs to exactly one triple of B. An MTS（v） （X,B） is called pure and denoted by PMTS（v） if （x, y, z） ∈ B implies （z, y, x） ∈B. A large set of MTS（v）s （LMTS（v）） is a collection of v - 2 pairwise disjoint MTS（v）s on a v-set. A self-converse large set of PMTS（v）s, denoted by LPMTS＊ （v）, is an LMTS（v） containing [ v-2/2] converse pairs of PMTS（v）s. In this paper, some results about the existence and non-existence for LPMTS＊ （v） are obtained.

Large Sets and Overlarge Sets of Triangle-Decomposition

There are six types of triangles： undirected triangle, cyclic triangle, transitive triangle, mixed-1 triangle, mixed-2 triangle and mixed-3 triangle. The triangle-decompositions for the six types of triangles have already been solved. For the first three types of triangles, their large sets have already been solved, and their overlarge sets have been investigated. In this paper, we establish the spectrum of LTi（v,λ）, OLTi（v）（i = 1, 2）, and give the existence of LT3（v, λ） and OLT3（v, λ） with λ even.

Tripling Construction for Large Sets of Resolvable Directed Triple Systems

In this paper, we first define a doubly transitive resolvable idempotent quasigroup （DTRIQ）, and show that aDTRIQ of order v exists if and only ifv ≡0（mod3） and v ≠ 2（mod4）. Then we use DTRIQ to present a tripling construction for large sets of resolvable directed triple systems, which improves an earlier version of tripling construction by Kang （J. Combin. Designs, 4 （1996）, 301-321）. As an application, we obtain an LRDTS（4·3^n） for any integer n ≥ 1, which provides an infinite family of even orders.

Large Sets of Pure Directed Triple Systems with Index λ

A directed triple system of order v with index λ, briefly by DTS（v,λ）, is a pair （X, B） where X is a v-set and B is a collection of transitive triples （blocks） on X such that every ordered pair of X belongs to λ blocks of B. A simple DTS（v, λ） is a DTS（v, λ） without repeated blocks. A simple DTS（v, ）,） is called pure and denoted by PDTS（v, λ） if （x, y, z） ∈ B implies （z, y, x）, （z, x, y）, （y, x, z）, （y, z, x）, （x, z, y） B. A large set of disjoint PDTS（v, λ）, denoted by LPDTS（v, λ）, is a collection of 3（v - 2）/λ disjoint pure directed triple systems on X. In this paper, some results about the existence for LPDTS（v, λ） are presented. Especially, we determine the spectrum of LPDTS（v, 2）.

A New Class for Large Sets of Almost Hamilton Cycle Decompositions

A k-cycle system of order v with index A, denoted by CS（v, k, λ）, is a collection A of k-cycles （blocks） of Kv such that each edge in Kv appears in exactly λ blocks of A. A large set of CS（v, k, λ）s is a partition of the set of all k-cycles of Kv into CS（v, k, λ）s, and is denoted by LCS（v, k, λ）. A （v - 1）-cycle in K, is called almost Hamilton. The completion of the existence problem for LCS（v, v- 1,λ） depends only on one case： all v ≥ 4 for λ=2. In this paper, it is shown that there exists an LCS（v,v - 1,2） for all v ≡ 2 （mod 4）, v ≥ 6.

Self-converse Large Sets of Pure Hybrid Triple Systems

A hybrid triple system of order v, briefly by HTS （v）, is a pair （X,/3） where X is a v-set and /3 is a collection of cyclic and transitive triples （called blocks） on X such that every ordered pair of X belongs to exactly one block of/3. An HTS （v） is called pure and denoted by PHTS （v） if one element of the block set {（x,y,z）, （z,y, ss）, （z,sc,y）, （y,x,z）, （y,z,x）, （x,z,y）, （x,y,z）, （z,y,x）} is contained in 13 then the others will not be contained in/3. A self-converse large set of disjoint PHTS （v）s, denoted by LPHTS＊（v）, is a collection of 4（v - 2） disjoint PHTS （v）s which contains exactly （v - 2）/2 converse octads of PHTS （v）s. In this paper, some results about the existence for LPHTS＊ （v） are obtained.

More Large Sets of Resolvable MTS and DTS with Even Orders

In this paper, we first introduce a special structure that allows us to construct a large set of resolvable Mendelsohn triple systems of orders 2q ＋ 2, or LRMTS（2q ＋ 2）, where q = 6t ＋ 5 is a prime power. Using a computer, we find examples of such structure for t C T = {0, 1, 2, 3, 4, 6, 7, 8, 9, 14, 16, 18, 20, 22, 24}. Furthermore, by a method we introduced in [13], large set of resolvable directed triple systems with the same orders are obtained too. Finally, by the tripling construction and product construction for LRMTS and LRDTS introduced in [2, 20, 21], and by the new results for LR-design in [8], we obtain the existence for LRMTS（v）and LRDTS（v）, where v = 12（t ＋ 1） mi≥0（2.7mi＋1）mi≥0（2.13ni＋1）and t∈T,which provides more infinite family for LRMTS and LRDTS of even orders.

Indecomposable Large Sets of Steiner Triple Systems with Indices 5, 6

A family （X, B1）,（X, B2）,..., （X, Bq） of q STS（v）s is a λ-fold large set of STS（v） and denoted by LSTSλ（v） if every 3-subset of X is contained in exactly A STS（v）s of the collection. It is indecomposable and denoted by IDLSTSx（v） if there does not exist an LSTSx, （v） contained in the collection for any λ 〈 λ. In this paper, we show that for λ = 5, 6, there is an IDLSTSλ（v） for v ≡ 1 or 3 （rood 6） with the exception IDLSTS6（7）.

Geological Features,Mineralization Types and Metallogenic Setting of the Phlaythong Large Iron Deposit,Southern Laos

The Phlaythong large iron deposit in Shampasak of southern Laos,is located in the Kon Tum microblock （Fig.1A）,central-southern part of the Indo-China block,and the geographic coordinate of the central mining area is 14°43′04″ N and 106°07′02″ E.

Clustering method based on data division and partition

Many classical clustering algorithms do good jobs on their prerequisite but do not scale well when being applied to deal with very large data sets(VLDS).In this work,a novel division and partition clustering method(DP) was proposed to solve the problem.DP cut the source data set into data blocks,and extracted the eigenvector for each data block to form the local feature set.The local feature set was used in the second round of the characteristics polymerization process for the source data to find the global eigenvector.Ultimately according to the global eigenvector,the data set was assigned by criterion of minimum distance.The experimental results show that it is more robust than the conventional clusterings.Characteristics of not sensitive to data dimensions,distribution and number of nature clustering make it have a wide range of applications in clustering VLDS.

Multidimensional Multiplicative Combinatorial Properties of Dynamical Syndetic Sets

In this paper,it is shown that for a minimal system(X,G),if H is a normal subgroup of G with finite index n,then X can be decomposed into n components of closed sets such that each component is minimal under H-action.Meanwhile,we prove that for a residual set of points in a minimal system with finitely many commuting homeomorphisms,the set of return times to any non-empty open set contains arbitrarily long geometric progressions in multidimension,extending a previous result by Glasscock,Koutsogiannis and Richter.

The Existence of LHMTS(m^v) and LHDTS(m^v)

In this article, we establish the existence of an LHMTS（mv） for v ≡ 2 （mod 6） and m≡ 3 （mod 6）. Thus there exists an LHMTS（mv） if and only if v（v-1）m2 ≡ 0 （mod 3） except possibly for v=6, m≡ 1, 5 （mod 6） and m≠1. In the similar way, the existence of LHDTS（mv） is completely determined, i.e., there exists an LHDTS（mv） if and only if v（v-1）m2 ≡ 0 （mod 3）.