Articulation Points Research Articles

LocalTGEP: A Lightweight Edge Partitioner for Time-Varying Graph

Graph edge partitioning (GEP), the allocation of edges into different parts through cut vertices, is essential for the analytics of large-scale graphs. Most GEP models cannot be directly applied to a time-varying graph unless repartitioning the entire graph, which leads to a large consumption of resources. Although a few studies have focused on time-varying graph edge partitioning, they have ignored the memory consumption during the partitioning process. Therefore, a lightweight edge partitioner, referred to as LocalTGEP, broadening the application to time-varying graphs, is proposed herein. Three superiorities of LocalTGEP are highlighted as follows: 1) A satisfactory partitioning quality for a time-varying graph can be achieved without requiring global information owing to the local edge partitioning. 2) Memory consumption of the partitioner is significantly reduced using a novel storage framework of graph data in LocalTGEP. 3) The quality and efficiency of time-varying graph edge partitioning are optimized by designing the push and pop stages in LocalTGEP. Extensive experimental results obtained on 12 real-world graphs demonstrate that LocalTGEP outperforms rival algorithms in terms of memory consumption, partitioning quality, and efficiency.

Generalized connectivity in cubic fuzzy graphs with application in the trade deficit problem

Cubic fuzzy graphs (CFGs) offer greater utility as compared to interval-valued fuzzy graphs and fuzzy graphs due to their ability to represent the degree of membership for vertices and edges using both interval and fuzzy number forms. The significance of these concepts motivates us to analyze and interpret intricate networks, enabling more effective decision making and optimization in various domains, including transportation, social networks, trade networks, and communication systems. This paper introduces the concepts of vertex and edge connectivity in CFGs, along with discussions on partial cubic fuzzy cut nodes and partial cubic fuzzy edge cuts, and presents several related results with the help of some examples to enhance understanding. In addition, this paper introduces the idea of partial cubic α-strong and partial cubic δ-weak edges. An example is discussed to explain the motivation behind partial cubic α-strong edges. Moreover, it delves into the introduction of generalized vertex and edge connectivity in CFGs, along with generalized partial cubic fuzzy cut nodes and generalized partial cubic fuzzy edge cuts. Relevant results pertaining to these concepts are also discussed. As an application, the concept of generalized partial cubic fuzzy edge cuts is applied to identify regions that are most affected by trade deficits resulting from street crimes. Finally, the research findings are compared with the existing method to demonstrate their suitability and creativity.

Smaller kernels for two vertex deletion problems

In this paper we consider two vertex deletion problems. In the Block Vertex Deletion problem, the input is a graph G and an integer k, and the goal is to decide whether there is a set of at most k vertices whose removal from G result in a block graph (a graph in which every biconnected component is a clique). In the Pathwidth One Vertex Deletion problem, the input is a graph G and an integer k, and the goal is to decide whether there is a set of at most k vertices whose removal from G result in a graph with pathwidth at most one. We give a kernel for Block Vertex Deletion with O(k3) vertices and a kernel for Pathwidth One Vertex Deletion with O(k2) vertices. Our results improve the previous O(k4)-vertex kernel for Block Vertex Deletion (Agrawal et al., 2016 [1]) and the O(k3)-vertex kernel for Pathwidth One Vertex Deletion (Cygan et al., 2012 [3]).

Canonical decompositions and algorithmic recognition of spatial graphs

AbstractWe prove that there exists an algorithm for determining whether two piecewise-linear spatial graphs are isomorphic. In its most general form, our theorem applies to spatial graphs furnished with vertex colourings, edge colourings and/or edge orientations.We first show that spatial graphs admit canonical decompositions into blocks, that is, spatial graphs that are non-split and have no cut vertices, in a suitable topological sense. Then, we apply a result of Haken and Matveev in order to algorithmically distinguish these blocks.

The Asymmetrical Stop Inventory of Witzapan Nawat

AbstractThe stop inventory of Witzapan Nawat, a critically endangered indigenous language of El Salvador, has been traditionally described as consisting only of a voiceless series /p t k kw/. In this paper, I measure the voice onset time, consonant duration, and percent voicing in stops produced by five L1 Witzapan Nawat speakers. I find that, while /p t kw/ have acoustic characteristics of voiceless stops in practically all contexts, the velar stop in this language is better analyzed as a voiced velar stop /ɡ/ rather than /k/. This results in an asymmetrical and unusual stop system that is not predicted by some theories of phonemic inventory structure. For instance, markedness-based theories propose that /ɡ/ is more marked that /b d/ and predict that, if a language has one voiced stop, it would be /b/ or /d/ rather than /ɡ/. On the other hand, feature-systemic models predict that, if a language has a stop with the [+voice] feature at a given place of articulation, it will also tend to have this feature in stops at other points of articulation to maximize feature economy. The phonemic inventory of Witzapan Nawat contradicts these predictions. I explain the asymmetrical stop inventory of this language as the result of diachronic developments involving sound change and analogy, concluding that language change does not necessarily advance towards symmetry and that phonemic inventories are the reflection of their diachrony, as proposed by Evolutionary Phonology.

Network partition detection and recovery with the integration of unmanned aerial vehicle

SummaryWireless sensor and actor networks (WSANs) consist of nodes associated in an ad hoc manner to perform sensing tasks for information gathering and acting functions on the basis of gathered information. Connectivity is an essential requirement of large‐scale wireless networks, and WSANs are supposed to stay connected. The nodes in hostile environments are prone to failures such as battery depletion, physical damage, or hardware malfunction. The failure of some nodes, like cut vertex nodes, can partition the network into multiple network segments. Most of the solutions for network partition recovery proposed in the literature depend on the assumption that the network is obstacle‐free. However, an obstacle‐free environment is not possible in real‐life situations. In the last few decades, UAVs or drones have been engaged in various applications such as industrial inspections, remote sensing, agriculture, military, disaster relief, and so forth, UAVs can be employed to strengthen the connections in wireless networks by coordinating with ground nodes since they can render services in rough areas where ground nodes cannot provide services. Thus, our research is based on using UAVs as relay nodes to reconnect the disjoint partitions. This paper proposes two algorithms: Drone assisted partition recovery algorithm (DAPRA) and drone assisted detection and partition recovery algorithm (DADPRA). In both algorithms, partitions are detected by the sink node. In DAPRA sink node determines the failed cut‐vertex node and sends UAV to the location of the failed cut‐vertex node. In DADPRA algorithm, UAV identifies the failed cut‐vertex node and reconnects the disjoint network segments. DAPRA and DADPRA are analyzed according to the state‐of‐the‐art parameters, that is, recovery and detection time, UAV's travel distance, and the total messages transmitted. The proposed algorithms are compared with similar Distributed Partition Detection and Recovery using UAV (DPDRU) approach. The simulation results show the proposed algorithms detect network partitioning in less time as compared to DPDRU approach.

Link Residual Closeness of Graphs with Fixed Parameters

Abstract Link residual closeness is a newly proposed measure for network vulnerability. In this model, vertices are perfectly reliable and the links fail independently of each other. It measures the vulnerability even when the removal of links does not disconnect the graph. In this paper, we characterize those graphs that maximize the link residual closeness over the connected graphs with fixed order and one additional parameter such as connectivity, edge connectivity, bipartiteness, independence number, matching number, chromatic number, number of cut vertices and number of cut edges.

The Effect of Vertex and Edge Removal on Sombor Index

A vertex degree based topological index called the Sombor index was recently defined in 2021 by Gutman and has been very popular amongst chemists and mathematicians. We determine the amount of change of the Sombor index when some elements are removed from a graph. This is done for several graph elements, including a vertex, an edge, a cut vertex, a pendant edge, a pendant path, and a bridge in a simple graph. Also, pendant and non-pendant cases are studied. Using the obtained formulae successively, one can find the Sombor index of a large graph by means of the Sombor indices of smaller graphs that are just graphs obtained after removal of some vertices or edges. Sometimes, using iteration, one can manage to obtain a property of a really large graph in terms of the same property of many other subgraphs. Here, the calculations are made for a pendant and non-pendant vertex, a pendant and non-pendant edge, a pendant path, a bridge, a bridge path from a simple graph, and, finally, for a loop and a multiple edge from a non-simple graph. Using these results, the Sombor index of cyclic graphs and tadpole graphs are obtained. Finally, some Nordhaus–Gaddum type results are obtained for the Sombor index.

Articulatory phonetic errors and patterns in Thai BIPA speakers: A study at SWM School Thailand

The tendency for Bahasa Indonesia bagi Penutur Asing (BIPA) or Indonesian as a Foreign Language (IFL) speakers' pronunciation errors makes specific patterns from an articulatory phonetic perspective. This approach is still limited, and the competence in pronouncing language is challenging. This study analyzes articulatory phonetic errors of vowels and consonants of BIPA Songserm Wittaya Mulniti (SWM) School Thailand speakers to find their reasons and patterns. This type of qualitative research used the listening-involved-conversation data collection technique as well as the equivalence and distributional analysis methods. The results showed 671 pronunciation errors; 184 vowels and 389 consonants. The majority of vowel errors are double vowels [uwa], open front [a], and near-close near-back [ʊ] based on the proximity of the tongue positions, movements of the tongue, lip position, and English interference. The majority of consonant errors are apico-alveolar trill [r] and lateral [l], lamino-palatal [ɲ], and dorso-velar [ŋ] based on the articulator and points of articulation, the similarity of the air passages, movement of the vocal cords, interference of air currents, and the interference of another language. The patterns formed were tendencies based on most errors, replacements, omissions, additions, omissions-replacements, replacements-additions, cutting of syllables, and phoneme errors that change the morpheme. Therefore, many errors formed a series of similarities and structured patterns, especially for consonants that had different pronunciation rules from the mother tongue. Practically, this research can help BIPA teachers develop appropriate learning materials and strategies according to the error patterns and characteristics of learners when pronouncing the language.

Path planning for unmanned load–haul–dump machines based on a VHF_A* algorithm

This study aimed to address the low search efficiency, long planning time, and unsmooth path problems in narrow and curved underground mining cave environments using traditional path planning algorithms. Thus, a new path planning method (VFH_A *) based on VFA and A* is proposed for unmanned load–haul–dump (LHD) operating in underground mines. First, the trajectory of the LHD articulation point is considered, the nodes are extended using this point, and collision detection is performed. Notably, the extended nodes neither collide nor conform to the trajectory of the LHD. Second, the vector field histogram (VFH) algorithm is introduced, and the steering and collision threat costs are combined with the comprehensive cost function of the traditional A* algorithm to form the VFH_A* algorithm. Thus, the node with the lowest comprehensive cost is selected for expansion, and redundant nodes are eliminated from the searched node paths. Third, the path is smoothed via Bezier interpolation. This ensures that the LHD operates smoothly and prevents excessive changes in the articulation angle. The proposed method was evaluated using above-ground and underground simulations. Compared with A* and GA algorithms, the VFH_A* algorithm significantly improved the search efficiency and can efficiently generate safe and smooth task paths in different scenarios. The planning time for each scenario was reduced by 85%. Finally, tracking experiments were conducted on the planned task paths of 1.5 and 2.5 m/s, indicating that the tracking error was less than 0.23 m. Overall, the planned path meets the requirements of unmanned LHD, indicating that the proposed method can adapt to practical applications.

The m-Component Connectivity of Leaf-Sort Graphs

Connectivity plays an important role in measuring the fault tolerance of interconnection networks. As a special class of connectivity, m-component connectivity is a natural generalization of the traditional connectivity of graphs defined in terms of the minimum vertex cut. Moreover, it is a more advanced metric to assess the fault tolerance of a graph G. Let G=(V(G),E(G)) be a non-complete graph. A subset F(F⊆V(G)) is called an m-component cut of G, if G−F is disconnected and has at least m components (m≥2). The m-component connectivity of G, denoted by cκm(G), is the cardinality of the minimum m-component cut. Let CFn denote the n-dimensional leaf-sort graph. Since many structures do not exist in leaf-sort graphs, many of their properties have not been studied. In this paper, we show that cκ3(CFn)=3n−6 (n is odd) and cκ3(CFn)=3n−7 (n is even) for n≥3; cκ4(CFn)=9n−212 (n is odd) and cκ4(CFn)=9n−242 (n is even) for n≥4.

On Upward-Planar L-Drawings of Graphs

In an upward-planar L-drawing of a directed acyclic graph (DAG) each edge $e=(v,w)$ is represented as a polyline composed of a vertical segment with its lowest endpoint at the tail $v$ of $e$ and of a horizontal segment ending at the head $w$ of $e$. Distinct edges may overlap, but must not cross. Recently, upward-planar L-drawings have been studied for $st$-graphs, i.e., planar DAGs with a single source $s$ and a single sink $t$ containing an edge directed from $s$ to $t$. It is known that a plane $st$-graph, i.e., an embedded $st$-graph in which the edge $(s,t)$ is incident to the outer face, admits an upward-planar L-drawing if and only if it admits a bitonic $st$-ordering, which can be tested in linear time. % We study upward-planar L-drawings of DAGs that are not necessarily $st$-graphs. As a combinatorial result, we show that a plane DAG admits an upward-planar L-drawing if and only if it is a subgraph of a plane $st$-graph admitting a bitonic $st$-ordering. This allows us to show that not every tree with a fixed bimodal embedding admits an upward-planar L-drawing. Moreover, we prove that any directed acyclic cactus with a single source (or a single sink) admits an upward-planar L-drawing, which respects a given outerplanar~embedding if there are no transitive edges. On the algorithmic side, we consider DAGs with a single source (or a single sink). We give linear-time testing algorithms for these DAGs in two cases: (a) when the drawing must respect a prescribed embedding and (b) when no restriction is given on the embedding, but the underlying undirected graph is series-parallel. For the single-sink case of (b) it even suffices that each biconnected component is series-parallel.

Biological Reconstruction of Acromioclavicular Joint Ligament Using Semitendinosus Autograft: A Prospective Study on Functional Outcomes and Complications

Abstract Introduction: The acromioclavicular (AC) joint, a crucial point of shoulder articulation, facilitates overhead and across-the-body arm movements. Athletes, especially those in high-contact or fall-prone sports, frequently experience AC joint injuries. These injuries, based on the Rockwood classification, range from type I to type VI, with treatments varying accordingly. One innovative treatment method reconstructs both ligaments using a semitendinosus autograft, aiming for an anatomical and functional restoration of the joint. This study evaluates the outcomes and complications of this method. Methodology: Study design: A prospective study from January 2021 to July 2022. Data source: Patients with Rockwood type III to VI AC joint ligament disruptions treated at Osmania General Hospital. Sample size: 14 patients. Surgical Technique for Acromioclavicular Ligament Reconstruction: Detailed steps encompassing patient positioning, graft harvesting and preparation, surgical approach, graft fixation, and postoperative care. Results: A total of 14 patients with AC disruptions (12 men and 2 women) treated with semitendinosus reconstruction were followed up for 24 months. Out of 14, 13 were Rockwood type III and 1 was type V ACJ dislocations. The mean patient age was 41 years (25–59 years). Functional outcome was assessed according to the constant-Murley score, according to which 7 patients had excellent, 6 had good, and 1 had an adequate outcome. We had only 1 case of surgical site infection leading to delayed rehabilitation leading to loss of abduction. Discussion: AC joint disruptions represent a significant percentage of shoulder injuries, especially among young, active individuals. Conservative treatments are typical for lower-grade injuries, but high-grade injuries often necessitate more invasive approaches. Our study included 14 patients, focusing on a semitendinosus autograft reconstruction. The historical Weaver–Dunn procedure, though once popular, has been phased out due to recurrence and strength issues. Our method, avoiding the controversial coracoid tunnel drilling, has shown promising results with no recorded fractures. Conclusion: The semitendinosus autograft method, with its biological orientation for coracoclavicular ligament reconstruction, presents fewer complications, especially in terms of coracoid fractures and reduction losses.

Exploring the properties and applications of complex fuzzy cut vertices and bridges

Exploring the properties and applications of complex fuzzy cut vertices and bridges

On Cohomology of Quasitoric Manifolds over a Vertex Cut of a Finite Product of Simplices

On Cohomology of Quasitoric Manifolds over a Vertex Cut of a Finite Product of Simplices

Certain Types of Vertices in m-Polar Fuzzy Graphs

In this study, we explore the concept of m-polar fuzzy (mPF) detour g-eccentric nodes within m-polar fuzzy graphs (mPFGs). We delve into the idea of mPF detour g-interior nodes and mPF detour g-boundary nodes, examining their significance and properties. Additionally, we establish the relationship between mPF detour g-boundary vertices and mPF cut vertices.

Explaining the type of Mongolian "Khoomii" from the phonological articulation's point of view

Explaining the type of Mongolian "Khoomii" from the phonological articulation's point of view

Transboundary Livestock Network in Africa: How Circulate Pathogens and Where to Act to Prevent the Epizootics Spread?

Objectives: Transboundary animal diseases (TADs) of domestic ruminants are closely linked to livestock movements, consequently, understanding these latter provides information on the pathogen's dissemination pathways. This descriptive study, using the mapping and network analysis (NA) method, aims to characterize the cross-border mobility network of domestic ruminants on the African continent, to understand how it works, to identify the main countries controlling livestock mobility, to deduct their relationships with other countries, and finally, to highlight the articulation points of the network at which actions should be taken to stop the epizootics spread. Methodology: This is a synthetic, descriptive study, whose results make it possible to place it within the framework of epidemiological surveillance with a continental scope, aiming to guide the efforts of the concerned authorities. Based on deep documentary research, a total of 483 transhumant and commercial cross-border movements were identified. These movements were mapped by the geographic information system (GIS) to reconstruct the network of international movements between countries. The most regular movements, numbering 190 and constituting a more stable exchange network over time, were subjected to processing by the NA method, to highlight different indicators that permit the characterization of the network. The results obtained were then compared with health data on the distribution of the five main notifiable animal diseases circulating in the African continent in addition to rinderpest. All analyses were conducted using “R” software. Results: The centrality indicators enabled the identification of the main central countries, including the most active and unavoidable ones that contribute to diseases spread in Africa. They also made it possible to quantify their importance in the influence of movement, while the global measurements and network cohesion parameters showed that the latter is vulnerable to the spread of epizootics. This study revealed a strong livestock exchange relationship between 25 African countries, extending from nations on the Atlantic Ocean coasts to those of the Indian Ocean ones, which were found to be the most vulnerable to the establishment of contagious diseases. Different communities of countries whose livestock movements appear to be very cohesive and which presage significant mutual contamination have been highlighted. Certain African countries have proven to be key points in the articulation of flows between different countries and different regions and contribute significantly to the dissemination of diseases between the different regions of the continent. Accordingly, key countries where actions should be taken to stop the epizootics spread were identified. Conclusion: The results allowed a better understanding of diseases diffusion pathways through livestock movements across Africa and highlighted the main movement focal points which represent a high-risk of diseases spread, as well as the capacity to influence their diffusion through the control of the animal’s movement or the deployment of prophylactic actions at their level.

Study on the bearing characteristics of overrun hydraulic support under impact loading

In order to study the effects of stress change and adaptability of the overrun hydraulic stent under impact load, the rigid–flexible coupling numerical model of the stent is established using multi-body dynamics simulation software ADAMS. In the model, the stent is flexibilized using the HyperMesh module, and the column and jack are equivalently replaced with a spring damping system. By applying impact loads to different positions above the front roof beam of the stent, the dynamic response characteristics of the column and the articulation point are obtained at different positions with different strengths. The results show that when the impact load is applied to different positions of the front roof beam, the steady-state response force of the column shows an overall “M" distribution, and along the length direction of the roof beam, the steady-state response force of the column shows an upward trend, and the maximum steady-state response force of the column is 547 kN at point (1, 6); when the impact load is applied to both sides of the front roof beam, the response at the articulation point is greater, resulting in a higher maximum simple harmonic response at that articulation point. When the impact load acts on both sides of the front roof beam, the response of the articulation point is greater, with a maximum simple harmonic response coefficient of 0.75 and a maximum excitation response coefficient of 0.28; when the impact loads of different strengths act on the whole front roof beam, the force acting on the column and pin shaft at the articulation point will produce a large impact, reducing its adaptability. To address this, we can consider changing the top plate stress conditions using methods like high-pressure injection of water and control the gradual and slow release of the top plate stresses. The results of the study provide a reference for the structural strength design and reliability analysis of the hydraulic support, which is of practical significance and value for improving the safe mining of the coal mining face.

Fast winning strategies for Staller in the Maker–Breaker domination game

The Maker–Breaker domination game is played on a graph G by two players, called Dominator and Staller, who alternately choose a vertex that has not been played so far. Dominator wins the game if his moves form a dominating set. Staller wins if she plays all vertices from a closed neighborhood of a vertex v∈V(G). Dominator’s fast winning strategies were studied earlier. In this work, we concentrate on the cases when Staller has a winning strategy in the game. We introduce the invariant γSMB′(G) (resp., γSMB(G)) which is the smallest integer k such that, under any strategy of Dominator, Staller can win the game by playing at most k vertices, if Staller (resp., Dominator) plays first on the graph G.We prove some basic properties of γSMB(G) and γSMB′(G) and study the parameters’ changes under some operators as taking the disjoint union of graphs or deleting a cut vertex. We show that the inequality δ(G)+1≤γSMB′(G)≤γSMB(G) always holds and that for every three integers r,s,t with 2≤r≤s≤t, there exists a graph G such that δ(G)+1=r, γSMB′(G)=s, and γSMB(G)=t. We prove exact formulas for γSMB′(G) where G is a path or it is a tadpole graph which is obtained from the disjoint union of a cycle and a path by adding one edge between them.