bluuebunny/crossref_metadata_2025_split huggingface dataset:
PENGEMBANGAN DESA OLEAN SEBAGAI DESA WISATA EDUKASI MENUJU WISATA RAKYAT BERKELANJUTAN DI KABUPATEN SITUBONDO (WISATA EDUKASI HIDROPONIK OLEAN)
Authors: Harisandi Yudhistira , Anshory Muhammad Iqbal 
Published: January 2020

Desa Olean, Kecamatan Situbondo, Kabupaten Situbondo memiliki banyak potensi wisata yang baik. Tetapi perkembangan Desa Olean sebagai daya tarik wisata mengalami pasang surut. Desa Olean adalah Desa wisata yang belum banyak dikenal oleh masyarakat Kota Situbondo. Untungnya masyarakat Desa Olean cepat tanggap untuk mengelola dan meningkatkan sumber daya yang ada untuk mengangkat nama desa mereka. Untuk memberikan alternatif wisata yang lebih beragam lagi di bidang tanaman, maka Olean merencanakan mengembangkan diri sebagai Desa Wisata Edukasi, sehingga menjadi daya tarik wisata adalah seluruh desa beserta sistem kehidupannya. Desa wisata menawarkan pengalaman baru yaitu kehidupan alam pedesaan, udara segar, dan kehidupan yang jauh dari polusi dan kebisingan, dan keterlibatan dalam aktivitas masyarakat setempat dalam artian bahwa wisatawan tidak hanya melihat begitu saja keindahan alam, tetapi dapat hidup di dalamnya. Wisatawan dapat merasakan dan menikmati secara utuh alam dan sosial budaya di yang sudah dibuat oleh desa tersebut. Terkat hal tersebut, tujuan dari kegiatan pengabdian ini adalah (1) Pengembangan wisata edukasi yang berbasis masyarakat dan berkelanjutan, (2) Memberikan manfaat kepada masyarakat, yaitu dapat meningkatkan pendapan masyarakat, (3) Menjaga kelestarian Desa Olean dan untuk menghindari alih fungsi lahan yang tidak terkendali
IMPLEMENTASI MODEL PEMBELAJARAN COOPERATIVE SCRIPT DALAM PERKULIAHAN TEORI & PRAKTIK PEMBELAJARAN MENYIMAK SEBAGAI UPAYA PENINGKATAN PRESTASI, AKTIVITAS, DAN KETERAMPILAN BERBICARA PADA MAHASISWA
Authors: Triandy Rendy 
Published: January 2020

This study aims to determine the effectiveness of the application of cooperative script learning models in lectures Theory & Practice of Listening Learning as an effort to improve student achievement, activities, and speaking skills. Listening skills are one of the important language skills to be mastered by students, so appropriate strategies or learning models are needed in their application. The research method used in this study is an experimental research method with a pretest-posttest control group design research design. The population in this research were students programme of study in the Indonesian Language and Literature Education FKIP Unpas. The sample in this study was the first semester students Programme of Study in the Indonesian Language and Literature Education FKIP Unpas. Based on the results of data processing using the SPSS 25 application, the value of sig is obtained. (2-tailed) of 0,000 <0.05. This shows that Ha was accepted and Ho was rejected. Therefore, it can be interpreted that the learning outcomes, activities, and speaking skills of semester I students programme of study in the Indonesian Language and Literature Education FKIP Unpas increased in lectures on Theory and Practice of Listening Learning using Cooperative Script learning models.
The Existence of Strong Complete Mappings
Authors: Evans Anthony B. 
Published: January 2020

A strong complete mapping of a group $G$ is a bijection $\theta\colon G\to G$ for which both mappings $x\mapsto x\theta(x)$ and $x\mapsto x^{-1}\theta(x)$ are bijections. We characterize finite abelian groups that admit strong complete mappings, thus solving a problem posed by Horton in 1990. We also prove the existence of strong complete mappings for countably infinite groups. A corrigendum for this paper was added on 2 October 2018.
On the Unitary Cayley Graph of a Ring
Authors: Kiani Dariush , Molla Haji Aghaei Mohsen 
Published: January 2020

Let $R$ be a ring with identity. The unitary Cayley graph of a ring $R$, denoted by $G_{R}$, is the graph, whose vertex set is $R$, and in which $\{x,y\}$ is an edge if and only if $x-y$ is a unit of $R$. In this paper we find chromatic, clique and independence number of $G_{R}$, where $R$ is a finite ring. Also, we prove that if $G_{R} \simeq G_{S}$, then $G_{R/J_{R}} \simeq G_{S/J_{S}}$, where $\rm J_{R}$ and $\rm J_{S}$ are Jacobson radicals of $R$ and $S$, respectively. Moreover, we prove if $G_{R} \simeq G_{M_{n}(F)}$ then $R\simeq M_{n}(F)$, where $R$ is a ring and $F$ is a finite field. Finally, let $R$ and $S$ be finite commutative rings, we show that if $G_{R} \simeq G_{S}$, then $\rm R/ {J}_{R}\simeq S/J_{S}$.
Distinguishability of Infinite Groups and Graphs
Authors: Smith Simon M , Tucker Thomas W , Watkins Mark E 
Published: January 2020

The distinguishing number of a group $G$ acting faithfully on a set $V$ is the least number of colors needed to color the elements of $V$ so that no non-identity element of the group preserves the coloring. The distinguishing number of a graph is the distinguishing number of its automorphism group acting on its vertex set. A connected graph $\Gamma$ is said to have connectivity 1 if there exists a vertex $\alpha \in V\Gamma$ such that $\Gamma \setminus \{\alpha\}$ is not connected. For $\alpha \in V$, an orbit of the point stabilizer $G_\alpha$ is called a suborbit of $G$.We prove that every nonnull, primitive graph with infinite diameter and countably many vertices has distinguishing number $2$. Consequently, any nonnull, infinite, primitive, locally finite graph is $2$-distinguishable; so, too, is any infinite primitive permutation group with finite suborbits. We also show that all denumerable vertex-transitive graphs of connectivity 1 and all Cartesian products of connected denumerable graphs of infinite diameter have distinguishing number $2$. All of our results follow directly from a versatile lemma which we call The Distinct Spheres Lemma.
Arc-transitive Pentavalent Graphs of Order 4pq
Authors: Pan Jiangmin , Lou Bengong , Liu Cuifeng 
Published: January 2020

This paper determines all arc-transitive pentavalent graphs of order $4pq$, where $p,q\ge 5$ are distinct primes. The cases $q=1,2,3$ and $q=p$ is a prime have been treated previously by Hua et al. [Pentavalent symmetric graphs of order $2pq$, Discrete Math. 311 (2011), 2259-2267], Hua and Feng [Pentavalent symmetric graphs of order $8p$, J. Beijing Jiaotong University 35 (2011), 132-135], Guo et al. [Pentavalent symmetric graphs of order $12p$, Electronic J. Combin. 18 (2011), #P233] and Huang et al. [Pentavalent symmetric graphs of order four time a prime power, submitted for publication], respectively.
Polyhedral Embeddings of Snarks with Arbitrary Nonorientable Genera
Authors: Liu Wenzhong , Chen Yichao 
Published: January 2020

Mohar and Vodopivec [Combinatorics, Probability and Computing (2006) 15, 877-893] proved that for every integer $k$ ($k \geq 1$ and $k\neq 2$), there exists a snark which polyhedrally embeds in $\mathbb{N}_k$ and presented the problem: Is there a snark that has a polyhedral embedding in the Klein bottle? In the paper, we give a positive solution of the problem and strengthen Mohar and Vodopivec's result. We prove that for every integer $k$ ($k\geq 2$), there exists an infinite family of snarks with nonorientable genus $k$ which polyhedrally embed in $\mathbb{N}_k$. Furthermore, for every integer $k$ ($k> 0$), there exists a snark with nonorientable genus $k$ which polyhedrally embeds in $\mathbb{N}_k$.
On Slowly Percolating Sets of Minimal Size in Bootstrap Percolation
Authors: Benevides Fabricio , Przykucki Michał 
Published: January 2020

Bootstrap percolation, one of the simplest cellular automata, can be seen as a model of the spread of infection. In $r$-neighbour bootstrap percolation on a graph $G$ we assign a state, infected or healthy, to every vertex of $G$ and then update these states in successive rounds, according to the following simple local update rule: infected vertices of $G$ remain infected forever and a healthy vertex becomes infected if it has at least $r$ already infected neighbours. We say that percolation occurs if eventually every vertex of $G$ becomes infected. A well known and celebrated fact about the classical model of $2$-neighbour bootstrap percolation on the $n \times n$ square grid is that the smallest size of an initially infected set which percolates in this process is $n$. In this paper we consider the problem of finding the maximum time a $2$-neighbour bootstrap process on $[n]^2$ with $n$ initially infected vertices can take to eventually infect the entire vertex set. Answering a question posed by Bollobás we compute the exact value for this maximum showing that, for $n \ge 4$, it is equal to the integer nearest to $(5n^2-2n)/8$.
Connectivity for Random Graphs from a Weighted Bridge-Addable Class
Authors: McDiarmid Colin 
Published: January 2020

There has been much recent interest in random graphs sampled uniformly from the $n$-vertex graphs in a suitable structured class, such as the class of all planar graphs. Here we consider a general bridge-addable class $\cal A$ of graphs -- if a graph is in $\cal A$ and $u$ and $v$ are vertices in different components then the graph obtained by adding an edge (bridge) between $u$ and $v$ must also be in $\cal A$. Various bounds are known concerning the probability of a random graph from such a class being connected or having many components, sometimes under the additional assumption that bridges can be deleted as well as added. Here we improve or amplify or generalise these bounds (though we do not resolve the main conjecture). For example, we see that the expected number of vertices left when we remove a largest component is less than 2. The generalisation is to consider `weighted' random graphs, sampled from a suitable more general distribution, where the focus is on the bridges.
On Short Zero-Sum Subsequences of Zero-Sum Sequences
Authors: Fan Yushuang , Gao Weidong , Wang Guoqing , Zhong Qinghai , Zhuang Jujuan 
Published: January 2020

Let $G$ be a finite abelian group of exponent $\exp(G)$. By $D(G)$ we denote the smallest integer $d\in \mathbb N$ such that every sequence over $G$ of length at least $d$ contains a nonempty zero-sum subsequence. By $\eta(G)$ we denote the smallest integer $d\in \mathbb N$ such that every sequence over $G$ of length at least $d$ contains a zero-sum subsequence $T$ with length $|T|\in [1,\exp(G)]$, such a sequence $T$ will be called a short zero-sum sequence. Let $C_0(G)$ denote the set consists of all integer $t\in [D(G)+1,\eta(G)-1]$ such that every zero-sum sequence of length exactly $t$ contains a short zero-sum subsequence. In this paper, we investigate the question whether $C_0(G)\neq \emptyset$ for all non-cyclic finite abelian groups $G$. Previous results showed that $C_0(G)\neq \emptyset$ for the groups $C_n^2$ ($n\geq 3$) and $C_3^3$. We show that more groups including the groups $C_m\oplus C_n$ with $3\leq m\mid n$, $C_{3^a5^b}^3$, $C_{3\times 2^a}^3$, $C_{3^a}^4$ and $C_{2^b}^r$ ($b\geq 2$) have this property. We also determine $C_0(G)$ completely for some groups including the groups of rank two, and some special groups with large exponent.
T-systems with Boundaries from Network Solutions
Authors: Di Francesco Philippe , Kedem Rinat 
Published: January 2020

In this paper, we use the network solution of the $A_r$ $T$-system to derive that of the unrestricted $A_\infty$ $T$-system, equivalent to the octahedron relation. We then present a method for implementing various boundary conditions on this system, which consists of picking initial data with suitable symmetries. The corresponding restricted $T$-systems are solved exactly in terms of networks. This gives a simple explanation for phenomena such as the Zamolodchikov periodicity property for $T$-systems (corresponding to the case $A_\ell\times A_r$) and a combinatorial interpretation for the positive Laurent property for the variables of the associated cluster algebra. We also explain the relation between the $T$-system wrapped on a torus and the higher pentagram maps of Gekhtman et al.
General Restriction of $(s,t)$-Wythoff's Game
Authors: Liu Wen An , Li Haiyan 
Published: January 2020

A.S. Fraenkel introduced a new $(s,t)$-Wythoff's game which is a generalization of both Wythoff's game and $a$-Wythoff's game. Four new models of a restricted version of $(s,t)$-Wythoff's game, Odd-Odd $(s,t)$-Wythoff's Game, Even-Even $(s,t)$-Wythoff's Game, Odd-Even $(s,t)$-Wythoff's Game and Even-Odd $(s,t)$-Wythoff's Game, are investigated. Under normal or misère play conventions, all $P$-positions of these four models are given for arbitrary integers $s,t\geq 1$. For Even-Even $(s,t)$-Wythoff's Game, the structure of $P$-positions is given by recursive characterizations in terms of the mex function. For other models, the structures of $P$-positions are of algebraic form, which permit us to decide in polynomial time whether or not a given game position $(a,b)$ is a $P$-position.
On the Characteristic Polynomial of $n$-Cayley Digraphs
Authors: Arezoomand Majid , Taeri Bijan 
Published: January 2020

A digraph $\Gamma$ is called $n$-Cayley digraph over a group $G$‎, ‎if there exists a semiregular subgroup $R_G$ of Aut$(\Gamma)$ isomorphic to $G$ with $n$ orbits‎. ‎In this paper‎, ‎we represent the adjacency matrix of $\Gamma$ as a diagonal block‎ ‎matrix in terms of irreducible representations of $G$ and determine its characteristic polynomial‎. ‎As corollaries of this result we find‎: ‎the spectrum of semi-Cayley graphs over abelian groups‎, ‎a relation between the characteristic polynomial of an $n$-Cayley graph and its complement‎, ‎and the spectrum of‎ ‎Calye graphs over groups with cyclic subgroups‎. ‎Finally we determine the eigenspace of $n$-Cayley digraphs and their main eigenvalues‎.
Stirling Numbers of Forests and Cycles
Authors: Galvin David , Thanh Do Trong 
Published: January 2020

For a graph $G$ and a positive integer $k$, the graphical Stirling number $S(G,k)$ is the number of partitions of the vertex set of $G$ into $k$ non-empty independent sets. Equivalently it is the number of proper colorings of $G$ that use exactly $k$ colors, with two colorings identified if they differ only on the names of the colors. If $G$ is the empty graph on $n$ vertices then $S(G,k)$ reduces to $S(n,k)$, the familiar Stirling number of the second kind.In this note we first consider Stirling numbers of forests. We show that if $(F^{c(n)}_n)_{n\geq 0}$ is any sequence of forests with $F^{c(n)}_n$ having $n$ vertices and $c(n)=o(\sqrt{n/\log n})$ components, and if $X^{c(n)}_n$ is a random variable that takes value $k$ with probability proportional to $S(F^{c(n)}_n,k)$ (that is, $X^{c(n)}_n$ is the number of classes in a uniformly chosen partition of $F^{c(n)}_n$ into non-empty independent sets), then $X^{c(n)}_n$ is asymptotically normal, meaning that suitably normalized it tends in distribution to the standard normal. This generalizes a seminal result of Harper on the ordinary Stirling numbers. Along the way we give recurrences for calculating the generating functions of the sequences $(S(F^c_n,k))_{k \geq 0}$, show that these functions have all real zeroes, and exhibit three different interlacing patterns between the zeroes of pairs of consecutive generating functions.We next consider Stirling numbers of cycles. We establish asymptotic normality for the number of classes in a uniformly chosen partition of $C_n$ (the cycle on $n$ vertices) into non-empty independent sets. We give a recurrence for calculating the generating function of the sequence $(S(C_n,k))_{k \geq 0}$, and use this to give a direct proof of a log-concavity result that had previously only been arrived at in a very indirect way.
Gromov Hyperbolicity in Strong Product Graphs
Authors: Carballosa Walter , Casablanca Rocío M. , De la Cruz Amauris , Rodríguez José M. 
Published: January 2020

If X is a geodesic metric space and $x_1,x_2,x_3\in X$, a geodesic triangle $T=\{x_1,x_2,x_3\}$ is the union of the three geodesics $[x_1x_2]$, $[x_2x_3]$ and $[x_3x_1]$ in $X$. The space $X$ is $\delta$-hyperbolic $($in the Gromov sense$)$ if any side of $T$ is contained in a $\delta$-neighborhood of the union of the two other sides, for every geodesic triangle $T$ in $X$. If $X$ is hyperbolic, we denote by $\delta (X)$ the sharp hyperbolicity constant of $X$, i.e., $\delta (X)=\inf\{\delta\geq 0: \, X \, \text{ is $\delta$-hyperbolic}\,\}\,.$ In this paper we characterize the strong product of two graphs $G_1\boxtimes G_2$ which are hyperbolic, in terms of $G_1$ and $G_2$: the strong product graph $G_1\boxtimes G_2$ is hyperbolic if and only if one of the factors is hyperbolic and the other one is bounded. We also prove some sharp relations between $\delta (G_1\boxtimes G_2)$, $\delta (G_1)$, $\delta (G_2)$ and the diameters of $G_1$ and $G_2$ (and we find families of graphs for which the inequalities are attained). Furthermore, we obtain the exact values of the hyperbolicity constant for many strong product graphs.
Knots in Collapsible and Non-Collapsible Balls
Authors: Benedetti Bruno , Lutz Frank H. 
Published: January 2020

We construct the first explicit example of a simplicial 3-ball $B_{15,66}$ that is not collapsible. It has only 15 vertices. We exhibit a second 3-ball $B_{12,38}$ with 12 vertices that is collapsible and not shellable, but evasive. Finally, we present the first explicit triangulation of a 3-sphere $S_{18, 125}$ (with only 18 vertices) that is not locally constructible. All these examples are based on knotted subcomplexes with only three edges; the knots are the trefoil, the double trefoil, and the triple trefoil, respectively. The more complicated the knot is, the more distant the triangulation is from being polytopal, collapsible, etc. Further consequences of our work are:(1) Unshellable 3-spheres may have vertex-decomposable barycentric subdivisions. (This shows the strictness of an implication proven by Billera and Provan.)(2) For $d$-balls, vertex-decomposable implies non-evasive implies collapsible, and for $d=3$ all implications are strict. (This answers a question by Barmak.)(3) Locally constructible 3-balls may contain a double trefoil knot as a 3-edge subcomplex. (This improves a result of Benedetti and Ziegler.)(4) Rudin's ball is non-evasive.
Shattering, Graph Orientations, and Connectivity
Authors: Kozma László , Moran Shay 
Published: January 2020

We present a connection between two seemingly disparate fields: VC-theory and graph theory. This connection yields natural correspondences between fundamental concepts in VC-theory, such as shattering and VC-dimension, and well-studied concepts of graph theory related to connectivity, combinatorial optimization, forbidden subgraphs, and others.In one direction, we use this connection to derive results in graph theory. Our main tool is a generalization of the Sauer-Shelah Lemma (Pajor, 1985; Bollobás and Radcliffe, 1995; Dress, 1997; Holzman and Aharoni). Using this tool we obtain a series of inequalities and equalities related to properties of orientations of a graph. Some of these results appear to be new, for others we give new and simple proofs.In the other direction, we present new illustrative examples of shattering-extremal systems - a class of set-systems in VC-theory whose understanding is considered by some authors to be incomplete Bollobás and Radcliffe, 1995; Greco, 1998; Rónyai and Mészáros, 2011). These examples are derived from properties of orientations related to distances and flows in networks.
Tree Reconstruction from Triplet Cover Distances
Authors: Huber Katharina T. , Steel Mike 
Published: January 2020

It is a classical result that any finite tree with positively weighted edges, and without vertices of degree 2, is uniquely determined by the weighted path distance between each pair of leaves. Moreover, it is possible for a (small) strict subset $\mathcal{L}$ of leaf pairs to suffice for reconstructing the tree and its edge weights, given just the distances between the leaf pairs in $\mathcal{L}$. It is known that any set ${\mathcal L}$ with this property for a tree in which all interior vertices have degree 3 must form a cover for $T$ - that is, for each interior vertex $v$ of $T$, ${\mathcal L}$ must contain a pair of leaves from each pair of the three components of $T-v$. Here we provide a partial converse of this result by showing that if a set ${\mathcal L}$ of leaf pairs forms a cover of a certain type for such a tree $T$ then $T$ and its edge weights can be uniquely determined from the distances between the pairs of leaves in ${\mathcal L}$. Moreover, there is a polynomial-time algorithm for achieving this reconstruction. The result establishes a special case of a recent question concerning 'triplet covers', and is relevant to a problem arising in evolutionary genomics.
Decomposing Dense Bipartite Graphs into 4-Cycles
Authors: Cavenagh Nicholas 
Published: January 2020

Let $G$ be an even bipartite graph with partite sets $X$ and $Y$ such that $|Y|$ is even and the minimum degree of a vertex in $Y$ is at least $95|X|/96$. Suppose furthermore that the number of edges in $G$ is divisible by $4$. Then $G$ decomposes into 4-cycles.
Zero-Sum Magic Labelings and Null Sets of Regular Graphs
Authors: Akbari Saieed , Rahmati Farhad , Zare Sanaz 
Published: January 2020

For every $h\in \mathbb{N}$, a graph $G$ with the vertex set $V(G)$ and the edge set $E(G)$ is said to be $h$-magic if there exists a labeling $l : E(G) \rightarrow\mathbb{Z}_h \setminus \{0\}$ such that the induced vertex labeling $s : V (G) \rightarrow \mathbb{Z}_h$, defined by $s(v) =\sum_{uv \in E(G)} l(uv)$ is a constant map. When this constant is zero, we say that $G$ admits a zero-sum $h$-magic labeling. The null set of a graph $G$, denoted by $N(G)$, is the set of all natural numbers $h \in \mathbb{ N} $ such that $G$ admits a zero-sum $h$-magic labeling. In 2012, the null sets of 3-regular graphs were determined. In this paper we show that if $G$ is an $r$-regular graph, then for even $r$ ($r > 2$), $N(G)=\mathbb{N}$ and for odd $r$ ($r\neq5$), $\mathbb{N} \setminus \{2,4\}\subseteq N(G)$. Moreover, we prove that if $r$ is odd and $G$ is a $2$-edge connected $r$-regular graph ($r\neq 5$), then $ N(G)=\mathbb{N} \setminus \{2\}$. Also, we show that if $G$ is a $2$-edge connected bipartite graph, then $\mathbb{N} \setminus \{2,3,4,5\}\subseteq N(G)$.
New Infinite Families of Congruences Modulo 8 for Partitions with Even Parts Distinct
Authors: Xia Ernest X. W. 
Published: January 2020

Let $ped(n)$ denote the number of partitions of an integer $n$ wherein even parts are distinct. Recently, Andrews, Hirschhorn and Sellers, Chen, and Cui and Gu have derived a number of interesting congruences modulo 2, 3 and 4 for $ped(n)$. In this paper we prove several new infinite families of congruences modulo 8 for $ped(n)$. For example, we prove that for $ \alpha \geq 0$ and $n\geq 0$,\[ ped\left(3^{4\alpha+4}n+\frac{11\times 3^{4\alpha+3}-1}{8}\right)\equiv 0 \ ({\rm mod \ 8}).\]