bluuebunny/crossref_metadata_2025 huggingface dataset:
Pembuatan Game Puzzle Online Dengan Prinsip Kooperatif Berbasis Android
Authors: Bimantara Tofan , Asri Sri Dianing
Published: January 2020

Perkembangan game online di Indonesia sangat pesat dan sangat diminati oleh banyak kalangan dari anak-anak sampai dewasa. Game online sangat digemari karena  adanya sistem PVP(player vs player) dimana pemain bisa melawan pemain lain secara online. Game PVP membuat para pemainya menjadi lebih kompetitif yang memaksa pemain bermain lebih intensif agar mendapatkan level atau peringkat lebih tinggi. intensif bermain berpengaruh pada agresivitas pemain sehingga membuat perilaku kurang menghargai sesama pemain seperti mengeluarkan kata-kata makian kepada pemain lain.  online juga memiliki sistem yang tidak cocok untuk anak kecil seperti adanya microtransaction dan sistem gacha. hal tersebut berakibatkan banyak anak melakukan transaksi tanpa sepengetahuan orang tuanya bahkan menghabiskan sampai puluhan juta rupiah. belum lagi sistem gacha  yaitu pembelian item secara acak dimana penggunanya belum tentu mendapatkan item yang diinginkan.  oleh karena itu penulis ingin membangun aplikasi game dengan prinsip kooperatif  yang pantas dimainkan anak-anak. Dalam pembuatan aplikasi game “Astam Eva” ini menggunakan metode MDLC(Multimedia Development Life Cycle). MDLC sendiri memiliki tahapan-tahapan yaitu Concept, Design, Material Collecting, Assembly, Testing, dan Distribution
Patriotyczne postawy polskich sportowców olimpijczyków w czasie II wojny światowej
Authors: Kołbuk Anna
Published: January 2020

Sport jako forma zorganizowanej rywalizacji od wieków jest nieodłączną częścią kultury w różnych cywilizacjach. Tak było również w Polsce od XIX wieku, kiedy pod zaborami zaczęły pojawiać się pierwsze stowarzyszenia i kluby sportowe. Sportowcy nie tylko promowali rozwój fizyczny i ducha rywalizacji wśród młodych ludzi, ale także kształtowali postawy patriotyczne. W Polsce, która odzyskała niepodległość po pierwszej wojnie światowej, sport stał się jedną z najpopularniejszych niekomercyjnych dziedzin życia, jednocząc różne środowiska, dostarczając emocji i przynosząc wiele sukcesów. Kulminacją kariery wielu sportowców był udział w igrzyskach olimpijskich, uważanych za największe święto sportów wyczynowych na świecie. Polscy przedstawiciele (ogółem 288) brali udział w ośmiu igrzyskach w okresie międzywojennym. Druga wojna światowa stała się czasem wielkiego patriotyzmu polskich sportowców olimpijskich. Zdecydowana większość z nich wykazała się godnością i odwagą, nierzadko poświęcając własne życie: w bitwach na różnych frontach, w ruchu oporu, w podziemiu, w obozach zagłady i egzekucji. Niektórzy z nich przenieśli się z dala od okupowanej Polski z powodu wojny, inni pozostali na wygnaniu do końca życia. Niektórzy polscy sportowcy olimpijscy współpracowali z okupantami niemieckimi i sowieckimi (zwykle pod przymusem). Sportowcy często też służyli ojczyźnie po wojnie ze względu na swoje doświadczenia wojenne.
Poświecenie niejedno ma imię
Authors: Lusek Joanna
Published: January 2020

Matylda Stefania Anna Ustjanowicz przyszła na świat 12 marca 1875 r. w Szczakowej nieopodal Chrzanowa. Celem otrzymania wykształcenia została wysłana do szkoły ss. niepokalanek w Niżniowie, gdzie ukończyła szkołę powszechną i średnią, prowadzoną wg koncepcji wychowawczej założycielki Zgromadzenia Sióstr Niepokalanego Poczęcia NMP – Marceliny Darowskiej. W latach 1893–1894 Matylda Ustjanowicz przygotowywała się pod okiem sióstr do zawodu nauczycielki domowej. W 1894 r. złożyła egzamin maturalny w Państwowym Seminarium Nauczycielskim Żeńskim we Lwowie. W kolejnych latach pracowała jako nauczyciela domowa.

Dnia 7 grudnia 1899 r. Matylda Ustjanowicz wstąpiła do Zgromadzenia Sióstr Niepokalanego Poczęcia NMP w Jazłowcu. Przyjęła imię zakonne Zofia od Serca Jezusowego. Śluby wieczyste złożyła 5 maja 1907 r. Przed wybuchem I wojny światowej pracowała jako mistrzyni internatu i kierowniczka zakładu naukowo-wychowawczego w Niżniowie, w latach 1909–1920 była przełożoną tamtejszego klasztoru. Podczas I wojny światowej w zabudowaniach tegoż funkcjonował lazaret wojenny, gdzie pod czujnym okiem s. Zofii zakonnice niosły pomoc rannym, chorym i umierającym.

W latach dwudziestolecia międzywojennego s. Zofia pracowała jako nauczycielka i dyrektorka w szkołach średnich Zgromadzenia w Nowym Sączu i Jarosławiu. W tym czasie dokształcała się na licznych kursach katechetycznych, w 1927 r. złożyła egzamin na nauczyciela szkół średnich w zakresie historii. W 1934 r. została zatwierdzona na stanowisko dyrektorki Prywatnego Seminarium Nauczycielskiego Zgromadzenia w Maciejowie, w sierpniu 1939 r. objęła przełożeństwo klasztoru w tymże. W 1938 r. została uhonorowana Złotym Krzyżem Zasługi na polu szkolnictwa prywatnego. W kwietniu 1942 r. s. Zofia otrzymała polecenie objęcia stanowiska zastępczyni przełożonej, a następnie administratorki klasztoru w Nowym Sączu. W maju 1944 r. wróciła do Niżniowa. Zginęła śmiercią męczeńską, zamordowana przez nacjonalistów ukraińskich, 23 sierpnia 1944 r., w Rusiłowie nieopodal Jazłowca.
Unveiling the Microstructure Elements of President Rodrigo Duterte’s Interviews: A Political Discourse Analysis
Authors: Gatcho Al Ryanne
Published: January 2020

This descriptive qualitative study seeks to unravel the microstructure elements of the interviews of President Rodrigo Duterte and how he represents himself and his opponents using political discourse analysis. The corpora consisted of his 30 recent interviews at the time of writing this paper and were retrieved in an online archive of the Presidential Communications Operations Office (PCOO). The findings indicated that Duterte’s discourse has these various linguistic features: modality, attributions, disclaimer, presuppositions, validity claims, pronoun use, transitivity, passivation, number of game, lexicon, idioms, metaphors, intertextuality, and profanity. The study revealed that Duterte manipulatively uses language to reflect a positive representation of himself and negative representation of others, legitimizing his authority and delegitimizing those in opposition.
Communication Challenges in the Military Institution
Authors: Mokibelo Eureka
Published: January 2020

This paper examines communication challenges within the military institution in Botswana. There seems to be rigid ways of delivering messages which in the end impede smooth communication practices between senior personnel and their subordinates within the institution. This study adopted the qualitative analysis to interrogate issues underlying communication practices from military classrooms for three years. The target group was middle ranking officers in institution who take Communication and Study Skills course as a requirement for their study at the University of Botswana. Data were collected using open ended questionnaires, interviews and group discussions in the classrooms. The model of communication process and new media were used to benchmark the practices within the institution against what the concepts say. The findings indicated that indeed communication processes were marred with problems that hinder smooth transition of messages from the sender to the receiver and ended up frustrating the subordinates. The study concluded that revamping and sanitizing communication practices within the military institution was necessary through educating the leadership to address the barriers encountered.
Heat Transfer Analysis on Peristaltic Transport of a Jeffery Fluid in an Inclined Elastic Tube with Porous Walls
Authors: Manjunatha G. , Rajashekhar C. , Vaidya Hanumesh , Prasad K. V.
Published: January 2020

This article analyses the effects of heat transfer and thermal conductivity on the peristaltic transport of Jeffery fluid through an inclined elastic tube with porous walls. The velocity slip and convective boundary conditions are taken into account. The modeled governing equations are solved analytically by considering the long wavelength and small Reynolds number approximations. The closed-form solutions are obtained for velocity, flow rate, and the theoretical determination of flow rate is calculated with the help of equilibrium condition given by Rubinow and Keller. A parametric analysis has been presented to study the effects of Jeffery parameter, thermal conductivity, Darcy number, the angle of inclination, velocity slip, Biot number, amplitude ratio, Prandtl number, and Eckert number on velocity, flow rate, and temperature are scrutinized. The streamlines show that the bolus moves with the same speed as that of the wave and further the study reveals that an increase in the Biot number reduces the magnitude of the temperature.
Liking the sound of their own voices: A case of TV anchors and their shows
Authors: Shehzad Hassan , Zaman Dr Muhammad , Zahra Shane
Published: January 2020

The aim of this research paper was to tap the role of anchorpersons of talk shows in promotion of media agenda and shaping political reality through measuring correspondence between time consumed by the anchorpersons and panel of experts. For the purpose, systematic random sampling technique has been used to select prime time talk shows of Geo News for one year. On the basis of wide coverage, three issues memo gate, law and order and corruption were selected to gauge the relationship between the variables. The results show a significant correlation between slant for the issues and time consumed by the anchors has been observed on all the three issues. The results showed that more the time grabbed by anchorpersons, more the programs remained in unfavorable state towards government. The results also revealed that 71% of total talk shows’ time was grabbed by the anchorpersons while panel of experts allotted 29% percent time in the issues. Anchorpersons remained unfavorable and biased in its deliberations towards government to a great extent by snatching the maximum time of the programs for molding the public opinion in a certain direction.
Iconostasis of the Church of the Assumption of the Blessed Virgin Mary in Nakonechne village - the most complete iconostasis ensemble of the XVI century
Authors: Helytovych Mariia
Published: January 2020

The article contains an analysis of the iconostasis of the Assumption of Mary Church located in the vil. Nakonechne (Yavoriv district, Lviv region), which represents the most fully preserved iconostasis ensemble of the XVI century. For the first time, its reconstruction was completed taking into account all saved icons. The article deals with stylistic, iconographic and artistic features of this ensemble, as well as its connection with other iconostases of that time. More precisely, the dating of the monument is argued. In the article, the author suggests to consider an ensemble from Nakonechne as a phenomenon in the history of Ukrainian icon painting, which reflected the most characteristic tendencies that took place in the painting of the second half of the XVI century. The author traces his influence on the iconography of the end of the XVI – the beginning of the XVII century
Pemenuhan Hak Narapidana Memperoleh Pelatihan Kerja dan Upah atas Pekerjaan yang Layak
Authors: Akbar Akbar , Soewondo Slamet S. , Azisa Nur
Published: January 2020

Sistem pemasyarakatan bukan saja menjadikan narapidana sebagai objek, melainkan juga subjek atas kodratnya sebagai manusia. Sistem pemasyarakatan bertujuan untuk mengembalikan warga binaan pemasyarakatan sebagai warga yang baik di tengah masyarakat. Penelitian ini merupakan penelitian hukum empirik (empirical research). Penelitian dilakukan di Lembaga Pemasyarakatan Klas I Kota Makassar. Hasil penelitian menunjukkan bahwa pelaksanaan pemenuhan hak mendapatkan upah atau premi atas pekerjaan yang dilakukan oleh narapidana di Lapas Klas I Kota Makassar sudah dilaksanakan sesuai dengan Keputusan Menteri Kehakiman Nomor M.01-PP.02.01 Tahun 1990 terkait besaran upah yang diterima narapidana 50% sebagai insentif karya narapidana, 35% sebagai dana penunjang pembinaan narapidana, 15% disetor ke Kantor Kas Negara. Konsep ideal pemidanaan terhadap narapidana dengan metode pemberian pelatihan dan diperkerjakan dikombinasi dengan program asimilasi sekaligus memberikan pekerjaan yang layak bagi narapidana.
Tantangan Penjabaran Prinsip-prinsip Demokrasi dalam Pembentukan Peraturan Daerah
Authors: Gunawan Bambang Ady
Published: January 2020

Penelitian bertujuan untuk menganalisis penerapan prinsip-prinsip demokrasi dalam pembentukan peraturan daerah, serta factor-faktor yang mempengaruhi penerapan prinsip-prinsip demokrasi dalam pembentukan peraturan daerah. Penelitian dilakukan dengan menggunakan metode yuridis normatif. Hasil penelitian menunjukkan bahwa pembentukan peraturan daerah harus dilandaskan pada prinsip- prinsip demokrasi yang merupakan bagian dari asas-asas penyelenggaraan pemerintahan yang baik, yakni prinsip partisipatif, prinsip keterbukaan dan prinsip akuntabilitas. Implementasi ketiga prinsip tersebut dalam pembentukan peraturan daerah belum dapat terlaksana dengan baik dalam prosedur pembentukan dan materi muatan yang diatur, hal ini berpengaruh terhadap kualitas peraturan hukum daerah yang dibentuk. Dalam pembentukan peraturan daerah ada tiga faktor yang mempengaruhi penerapan prinsip- prinsip demokrasi yakni faktor substansi hukum, struktur hukum dan kultur hukum. Ditinjau dari faktor struktur, menunjukkan pemerintah daerah dan DPRD kurang memberikan ruang bagi masyarakat untuk menyampaikan aspirasi. Sedangkan dari aspke kultur hukum menunjukkan bahwa peran serta masyarakat sangat diperlukan dalam pembentukan daerah, peran serta masyarakat masih kurang dipahami oleh masyarakat itu sendiri sehingga kurang peduli terhadap pembentukan peraturan daerah.
Manajemen Risiko Pembiayaan Murabahah Pada Baitul Maal Wat Tamwil (BMT)
Authors: Abdul Djalil Nashrurrahman , Munir Ammar
Published: January 2020

Penelitian ini bertujuan untuk mengetahui praktik pembiayaan murabahah, risiko yang terkait dengan pembiayaan murabahah, dan cara mengatasi risiko yang terkait dengan pembiayaan bermasalah pada BMT di Makassar. Penelitian ini menggunakan desain kualitatif. Data penelitian ini diperoleh dari wawancara langsung dengan pihak-pihak terkait. Peneliti juga mengumpulkan dokumen-dokumen yang relevan dan mendukung pembahasan penelitian. Hasil penelitian menunjukkan praktik pembiayaan murabahah pada BMT di Makassar digunakan untuk pengadaan barang konsumsi maupun penambahan modal usaha (pembelian barang dagangan). Risiko yang dihadapi secara umum adalah kredit macet. Kredit macet dapat disebabkan oleh kebakaran atau penggusuran tempat usaha. Risiko lainnya yang dihadapi terkait dengan barang adalah rusak atau hilangnya barang yang sudah dibeli dalam masa angsuran. Risiko yang terkait dengan nasabah adalah nasabah yang berpindah tempat tanpa konfirmasi dengan pihak BMT, sakit, kematian atau karakter nasabah yang kurang baik. Risiko yang terkait pengelola BMT, yaitu tidak menyeleksi secara baik nasabah yang melakukan pembiayaan. Cara mengatasi risiko yang terkait pembiayaan bermasalah adalah dengan melakukan rescheduling, restructuring, dan eksekusi, yaitu dengan cara menjadwal ulang seluruh/sebagian kewajiban anggota, mengubah komposisi pembiayaan, menyita dan melelang barang jaminan untuk menutupi kewajiban anggota.
Sistem Penggarapan Lahan Pertanian Masyarakat: Perspektif Ekonomi Islam
Authors: Wahyu A. Rio Makkulau
Published: January 2020

Selain sebagai sumber kesediaan pangan, pertanian juga menjadi sebagai sumber penghasilan bagi masyarakat, khususnya di Kabupaten Sidrap, Sulawesi Selatan. Salah satu bentuk kerja sama di bidang pertanian yakni sistem muzara’ah (kerjasama antara pemilik lahan dengan penggarap dan benihnya dari pemilik lahan) dan mukhabarah (kerjasama antara pemilik lahan dengan penggarap dan benihnya dari penggerap). Studi ini dilakukan dengan menggunakan jenis penelitian deskriptif kualitatif dengan menggunakan sumber data primer dan sekunder yang dianalisis dengan teknik trianggulasi. Hasil analisis didapatkan bahwa didalam penggarapan lahan pertanian tersebut terdapat bentuk kerja sama antara pemilik lahan pertanian dengan penggarap lahan pertanian yang diikuti dengan sistem bagi hasil dengan besaran persentase 50% untuk pemilik lahan dan 50% untuk penggarap lahan dengan ketentuan sebagian biaya tertentu ditanggung bersama antara kedua pihak dan biaya yang lainya ditanggung penggarap lahan dengan bentuk perjanjian penggarapan lahan pertanian melalui sistem kerja sama yang diikuti dengan sistem bagi hasil yang tidak dibuat dalam bentuk tertulis karena masih menggunakan adat kebiasaan setempat.
Efektivitas Penerapan Zakat Online terhadap Peningkatan Pembayaran Zakat pada Lembaga Dompet Dhuafa Sulsel
Authors: Sakka Abdul Rahman , Qulub Latifatul
Published: January 2020

Zakat memiliki dimensi ketuhanan sekaligus dimensi kemanusiaan yang sangat kuat. Pada dimensi kemanusiaan, zakat punya peran penting dalam mendistribusikan kekayaan secara adil untuk mewujudkan kesejahteraan yang merata. Permasalahannya adalah pengelolaan khususnya pada pengumpulan zakat dari orang yang wajib berzakat belum terlaksana dengan baik. Dompet Dhuafa sebagai salah satu Lembaga Amil Zakat Nasional melakukan sistem pengumpulan zakat secara online sesuai dengan perkembangan teknologi internet yang semakin maju. Tulisan ini merupakan penelitian untuk melihat efektifitas system zakat online Dompet Dhuafa Sulawesi Selatan dalam mengumpulkan zakat dari para muzakki. Hasil penelitian menunjukkan bahwa pengumpulan zakat secara online melebihi 2% dari target yang dicanangkan. Dompet Dhuafa menargetkan pengumpulan zakat tahun 2017 sebanyak Rp.1.114.329.320 sedangkan yang dicapai sebanyak Rp1242957097. Dengan demikian penerapan sistem pembayaran zakat berbasis finance technology pada Dompet Dhuafa Sulawesi Selatan berjalan secara efektif
A Conceptual Model of Intrapreneurship in Banking Sector of Pakistan
Authors: Kanwal Nagina , Raju Valliappan , Zreen Aneeqa
Published: January 2020

This Study seeks to build a conceptual model of Intrapreneurial behavior among employees of banking sector of Pakistan. That model elaborates the concept of Intrapreneurship along with its prerequisites. The proposed model intends to elaborate the main factors affecting Intrapreneurship phenomenon and elaborates the constructs of Intrapreneurship that may affect organizational outcomes. Further, based on literature review, it also seeks to establish that organizational culture potentially moderates the relation between organizational factors and Intrapreneurial behaviour. This paper identifies and explains the existing and previous literature on prerequisites, phenomenon and outcomes of Intrapreneurial behaviour as a basis for analysis and establishing a model of Intrapreneurship in Banking Sector of Pakistan. This is a conceptual paper is based on previous research work that supports our proposed model. This conceptual paper provides a model for banking sector of Pakistan in which organizational factors effect Intrapreneurial behaviour and further investigates the impact of this behaviour on outcomes. The current study accompanies a number of researches that explain how Intrapreneurial behaviour contributes to the organizational outcomes in banking sector of Pakistan. This proposed frame work may help scholars in developing further studies that advocate Intrapreneurial behaviour as a source of improving business performance or outcomes. This study may explore the new insights about Intrapreneurship and its practical implications for banking sector of Pakistan and opportunities for further research are established.
Apéry's Double Sum is Plain Sailing Indeed
Authors: Schneider Carsten
Published: January 2020

We demonstrate that also the second sum involved in Apéry's proof of the irrationality of $\zeta(3)$ becomes trivial by symbolic summation.
A Bound for Size Ramsey Numbers of Multi-partite Graphs
Authors: Sun Yuqin , Li Yusheng
Published: January 2020

It is shown that the (diagonal) size Ramsey numbers of complete $m$-partite graphs $K_{m}(n)$ can be bounded from below by $cn^22^{(m-1)n}$, where $c$ is a positive constant.
Eigenvectors and Reconstruction
Authors: He Hongyu
Published: January 2020

In this paper, we study the simple eigenvectors of two hypomorphic matrices using linear algebra. We also give new proofs of results of Godsil and McKay.
New Infinite Families of $3$-Designs from Algebraic Curves of Higher Genus over Finite Fields
Authors: Oh Byeong-Kweon , Yu Hoseog
Published: January 2020

In this paper, we give a simple method for computing the stabilizer subgroup of $D(f)=\{\alpha \in {\Bbb F}_q \mid \text{ there is a } \beta \in {\Bbb F}_q^{\times} \text{ such that }\beta^n=f(\alpha)\}$ in $PSL_2({\Bbb F}_q)$, where $q$ is a large odd prime power, $n$ is a positive integer dividing $q-1$ greater than $1$, and $f(x) \in {\Bbb F}_q[x]$. As an application, we construct new infinite families of $3$-designs.
Encores on Cores
Authors: Cain Julie , Wormald Nicholas
Published: January 2020

We give a new derivation of the threshold of appearance of the $k$-core of a random graph. Our method uses a hybrid model obtained from a simple model of random graphs based on random functions, and the pairing or configuration model for random graphs with given degree sequence. Our approach also gives a simple derivation of properties of the degree sequence of the $k$-core of a random graph, in particular its relation to multinomial and hence independent Poisson variables. The method is also applied to $d$-uniform hypergraphs.
A Point in Many Triangles
Authors: Bukh Boris
Published: January 2020

We give a simpler proof of the result of Boros and Füredi that for any finite set of points in the plane in general position there is a point lying in $2/9$ of all the triangles determined by these points.
Combinatorial Proofs of Capelli's and Turnbull's Identities from Classical Invariant Theory
Authors: Foata Dominique , Zeilberger Doron
Published: January 2020

Capelli's identity plays a prominent role in Weyl's approach to Classical Invariant Theory. Capelli's identity was recently considered by Howe and Howe and Umeda. Howe gave an insightful representation-theoretic proof of Capelli's identity, and a similar approach was used to prove Turnbull's symmetric analog, as well as a new anti-symmetric analog, that was discovered independently by Kostant and Sahi. The Capelli, Turnbulll, and Howe-Umeda-Kostant-Sahi identities immediately imply, and were inspired by, identities of Cayley, Garding, and Shimura, respectively. In this paper, we give short combinatorial proofs of Capelli's and Turnbull's identities, and raise the hope that someone else will use our approach to prove the new Howe-Umeda-Kostant-Sahi identity.
On the Spectra of Certain Classes of Room Frames
Authors: Dinitz Jeffrey H. , Stinson Douglas R. , Zhu L.
Published: January 2020

In this paper we study the spectra of certain classes of Room frames. The three spectra are incomplete Room squares, uniform Room frames and Room frames of type $2^ut^1$. These problems have been studied in numerous papers over the years; in this paper, we complete the three spectra except for one possible exception in each case.
Bartholdi Zeta Functions of Fractal Graphs
Authors: Sato Iwao
Published: January 2020

Recently, Guido, Isola and Lapidus defined the Ihara zeta function of a fractal graph, and gave a determinant expression of it. We define the Bartholdi zeta function of a fractal graph, and present its determinant expression.
More Statistics on Permutation Pairs
Authors: Fedou Jean-Marc , Rawlings Don
Published: January 2020

Two inversion formulas for enumerating words in the free monoid by $\theta$-adjacencies are applied in counting pairs of permutations by various statistics. The generating functions obtained involve refinements of bibasic Bessel functions. We further extend the results to finite sequences of permutations.
The Problem of the Kings
Authors: Wilf Herbert S.
Published: January 2020

On a $2m\times 2n$ chessboard, the maximum number of nonattacking kings that can be placed is $mn$, since each $2\times 2$ cell can have at most one king. Let $f_m(n)$ denote the number of ways that $mn$ nonattacking kings can be placed on a $2m\times 2n$ chessboard. The purpose of this paper is to prove the following result. Theorem. For each $m=1,2,3,\ldots $ there are constants $c_m>0$, $d_m$, and $0\le \theta_m < m+1$ such that $$f_m(n)= (c_mn+d_m)(m+1)^n+O(\theta_m^n)\qquad (n\to\infty).$$
Counting Two-graphs Related to Trees
Authors: Cameron Peter J.
Published: January 2020

In an earlier paper, I showed that the classes of pentagon-free two-graphs and of pentagon-and-hexagon-free two-graphs could be represented in terms of trees. This paper gives formulae for the numbers of labelled objects in each of these classes, as well as the numbers of labelled reduced two-graphs in each class. The proofs use various enumeration results for trees. At least some of these results are well-known. To make the paper self-contained, I have included proofs.
The eigenvalues of the Laplacian for the homology of the Lie algebra corresponding to a poset
Authors: Hozo Iztok
Published: January 2020

In this paper we study the spectral resolution of the Laplacian ${\cal L}$ of the Koszul complex of the Lie algebras corresponding to a certain class of posets. Given a poset $P$ on the set $\{1,2,\dots,n\}$, we define the nilpotent Lie algebra $L_P$ to be the span of all elementary matrices $z_{x,y}$, such that $x$ is less than $y$ in $P$. In this paper, we make a decisive step toward calculating the Lie algebra homology of $L_P$ in the case that the Hasse diagram of $P$ is a rooted tree. We show that the Laplacian ${\cal L}$ simplifies significantly when the Lie algebra corresponds to a poset whose Hasse diagram is a tree. The main result of this paper determines the spectral resolutions of three commuting linear operators whose sum is the Laplacian ${\cal L}$ of the Koszul complex of $L_P$ in the case that the Hasse diagram is a rooted tree. We show that these eigenvalues are integers, give a combinatorial indexing of these eigenvalues and describe the corresponding eigenspaces in representation-theoretic terms. The homology of $L_P$ is represented by the nullspace of ${\cal L}$, so in future work, these results should allow for the homology to be effectively computed.
Exact Mixing in an Unknown Markov Chain
Authors: Lovasz Laszlo , Winkler Peter
Published: January 2020

We give a simple stopping rule which will stop an unknown, irreducible $n$-state Markov chain at a state whose probability distribution is exactly the stationary distribution of the chain. The expected stopping time of the rule is bounded by a polynomial in the maximum mean hitting time of the chain. Our stopping rule can be made deterministic unless the chain itself has no random transitions.
Dense Packings of Equal Disks in an Equilateral Triangle
Authors: Graham R. L. , Lubachevsky B. D.
Published: January 2020

Previously published packings of equal disks in an equilateral triangle have dealt with up to 21 disks. We use a new discrete-event simulation algorithm to produce packings for up to 34 disks. For each $n$ in the range $22 \le n \le 34$ we present what we believe to be the densest possible packing of $n$ equal disks in an equilateral triangle. For these $n$ we also list the second, often the third and sometimes the fourth best packings among those that we found. In each case, the structure of the packing implies that the minimum distance $d(n)$ between disk centers is the root of polynomial $P_n$ with integer coefficients. In most cases we do not explicitly compute $P_n$ but in all cases we do compute and report $d(n)$ to 15 significant decimal digits. Disk packings in equilateral triangles differ from those in squares or circles in that for triangles there are an infinite number of values of $n$ for which the exact value of $d(n)$ is known, namely, when $n$ is of the form $\Delta (k) := \frac{k(k+1)}{2}$. It has also been conjectured that $d(n-1) = d(n)$ in this case. Based on our computations, we present conjectured optimal packings for seven other infinite classes of $n$, namely \begin{align*} n & = & \Delta (2k) +1, \Delta (2k+1) +1, \Delta (k+2) -2 , \Delta (2k+3) -3, \\ && \Delta (3k+1)+2 , 4 \Delta (k), \text{ and } 2 \Delta (k+1) + 2 \Delta (k) -1 . \end{align*} We also report the best packings we found for other values of $n$ in these forms which are larger than 34, namely, $n=37$, 40, 42, 43, 46, 49, 56, 57, 60, 63, 67, 71, 79, 84, 92, 93, 106, 112, 121, and 254, and also for $n=58$, 95, 108, 175, 255, 256, 258, and 260. We say that an infinite class of packings of $n$ disks, $n=n(1), n(2),...n(k),...$, is tight , if [$1/d(n(k)+1) - 1/d(n(k))$] is bounded away from zero as $k$ goes to infinity. We conjecture that some of our infinite classes are tight, others are not tight, and that there are infinitely many tight classes.
The three dimensional polyominoes of minimal area
Authors: Alonso Laurent , Cerf Raphaël
Published: January 2020

The set of the three dimensional polyominoes of minimal area and of volume $n$ contains a polyomino which is the union of a quasicube $j\times (j+\delta)\times (j+\theta)$, $\delta,\theta\in\{0,1\}$, a quasisquare $l\times (l+\epsilon)$, $\epsilon\in\{0,1\}$, and a bar $k$. This shape is naturally associated to the unique decomposition of $n=j(j+\delta)(j+\theta)+l(l+\epsilon)+k$ as the sum of a maximal quasicube, a maximal quasisquare and a bar. For $n$ a quasicube plus a quasisquare, or a quasicube minus one, the minimal polyominoes are reduced to these shapes. The minimal area is explicitly computed and yields a discrete isoperimetric inequality. These variational problems are the key for finding the path of escape from the metastable state for the three dimensional Ising model at very low temperatures. The results and proofs are illustrated by a lot of pictures.
A Simple Method for Constructing Small Cubic Graphs of Girths 14, 15 and 16
Authors: Exoo Geoffrey
Published: January 2020

A method for constructing cubic graphs with girths in the range 13 to 16 is described. The method is used to construct the smallest known cubic graphs for girths 14, 15 and 16.
Stapled Sequences and Stapling Coverings of Natural Numbers
Authors: Gassko Irene
Published: January 2020

A stapled sequence is a set of consecutive positive integers such that no one of them is relatively prime with all of the others. The problem of existence and construction of stapled sequences of length $N$ was extensively studied for over 60 years by Pillai, Evans, Brauer, Harborth, Erdős and others.Sivasankaranarayana, Szekeres and Pillai proved that no stapled sequences exist for any $N < 17$. We give a new simple proof of this fact.There exist several proofs that stapled sequences exist for any $N \geq 17$. We show that existence of stapled sequences is equivalent to existence of stapling coverings of a sequence of $N$ consecutive natural numbers by prime arithmetic progressions such that each progression has at least two common elements with the sequence and discuss properties of stapling coverings. We introduce the concept of efficiency of stapling coverings and develop algorithms that produce efficient stapling coverings. Using the result by Erdős, we show that the greatest prime number used in stapling coverings of length $N$ can be made $o(N)$.
The Borwein Conjecture and Partitions with Prescribed Hook Differences
Authors: Bressoud David A.
Published: January 2020

Peter Borwein has conjectured that certain polynomials have non-negative coefficients. In this paper we look at some generalizations of this conjecture and observe how they relate to the study of generating functions for partitions with prescribed hook differences. A combinatorial proof of the generating function for partitions with prescribed hook differences is given.
Efficient Covering Designs of the Complete Graph
Authors: Caro Yair , Yuster Raphael
Published: January 2020

Let $H$ be a graph. We show that there exists $n_0=n_0(H)$ such that for every $n \geq n_0$, there is a covering of the edges of $K_n$ with copies of $H$ where every edge is covered at most twice and any two copies intersect in at most one edge. Furthermore, the covering we obtain is asymptotically optimal.
Magic N-Cubes Form a Free Monoid
Authors: Adler Allan
Published: January 2020

In this paper we prove a conjecture stated in an earlier paper [A-L]. The conjecture states that with respect to a rather natural operation, the set of $N$-dimensional magic cubes forms a free monoid for every integer $N>1$. A consequence of this conjecture is a certain identity of formal Dirichlet series. These series and the associated power series are shown to diverge. Generalizations of the underlying ideas are presented. We also prove variants of the main results for magic cubes with remarkable power sum properties.
Combinatorial Game Theory Foundations Applied to Digraph Kernels
Authors: Fraenkel Aviezri S.
Published: January 2020

Known complexity facts: the decision problem of the existence of a kernel in a digraph $G=(V,E)$ is NP-complete; if all of the cycles of $G$ have even length, then $G$ has a kernel; and the question of the number of kernels is $\#$P-complete even for this restricted class of digraphs. In the opposite direction, we construct game theory tools, of independent interest, concerning strategies in the presence of draw positions, to show how to partition $V$, in $O(|E|)$ time, into $3$ subsets $S_1,S_2,S_3$, such that $S_1$ lies in all the kernels; $S_2$ lies in the complements of all the kernels; and on $S_3$ the kernels may be nonunique. Thus, in particular, digraphs with a "large" number of kernels are those in which $S_3$ is "large"; possibly $S_1=S_2=\emptyset$. We also show that $G$ can be decomposed, in $O(|E|)$ time, into two induced subgraphs $G_1$, with vertex-set $S_1\cup S_2$, which has a unique kernel; and $G_2$, with vertex-set $S_3$, such that any kernel $K$ of $G$ is the union of the kernel of $G_1$ and a kernel of $G_2$. In particular, $G$ has no kernel if and only if $G_2$ has none. Our results hold even for some classes of infinite digraphs.
New symmetric designs from regular Hadamard matrices
Authors: Ionin Yury J.
Published: January 2020

For every positive integer $m$, we construct a symmetric $(v,k,\lambda )$-design with parameters $v={{h((2h-1)^{2m}-1)}\over{h-1}}$, $k=h(2h-1)^{2m-1}$, and $\lambda =h(h-1)(2h-1)^{2m-2}$, where $h=\pm 3\cdot 2^d$ and $|2h-1|$ is a prime power. For $m\geq 2$ and $d\geq 1$, these parameter values were previously undecided. The tools used in the construction are balanced generalized weighing matrices and regular Hadamard matrices of order $9\cdot 4^d$.
Bijective Recurrences concerning Schröder Paths
Authors: Sulanke Robert A.
Published: January 2020

Consider lattice paths in Z$^2$ with three step types: the up diagonal $(1,1)$, the down diagonal $(1,-1)$, and the double horizontal $(2,0)$. For $n \geq 1$, let $S_n$ denote the set of such paths running from $(0,0)$ to $(2n,0)$ and remaining strictly above the x-axis except initially and terminally. It is well known that the cardinalities, $r_n = |S_n|$, are the large Schröder numbers. We use lattice paths to interpret bijectively the recurrence $ (n+1) r_{n+1} = 3(2n - 1) r_{n} - (n-2) r_{n-1}$, for $n \geq 2$, with $r_1=1$ and $r_2=2$. We then use the bijective scheme to prove a result of Kreweras that the sum of the areas of the regions lying under the paths of $S_n$ and above the x-axis, denoted by $AS_n$, satisfies $ AS_{n+1} = 6 AS_n - AS_{n-1}, $ for $n \geq 2$, with $AS_1 =1$, and $AS_2 =7$. Hence $AS_n = 1, 7, 41, 239 ,1393, \ldots$. The bijective scheme yields analogous recurrences for elevated Catalan paths.
On the Total Weight of Weighted Matchings of Segment Graphs
Authors: Stoll Thomas , Zeng Jiang
Published: January 2020

We study the total weight of weighted matchings in segment graphs, which is related to a question concerning generalized Chebyshev polynomials introduced by Vauchassade de Chaumont and Viennot and, more recently, investigated by Kim and Zeng. We prove that weighted matchings with sufficiently large node-weight cannot have equal total weight.
Combinatorial statistics on type-B analogues of noncrossing partitions and restricted permutations
Authors: Simion Rodica
Published: January 2020

We define type-B analogues of combinatorial statistics previously studied on noncrossing partitions and show that analogous equidistribution and symmetry properties hold in the case of type-B noncrossing partitions. We also identify pattern-avoiding classes of elements in the hyperoctahedral group which parallel known classes of restricted permutations with respect to their relations to noncrossing partitions.
Some Bijective Correspondences Involving Domino Tableaux
Authors: Van Leeuwen Marc A. A.
Published: January 2020

We define a number of new combinatorial operations on skew semistandard domino tableaux that complement constructions defined by C. Carré and B. Leclerc, and clarify the link with ordinary skew semistandard tableaux and the Littlewood-Richardson rule. These operations are: (1) a bijection between semistandard domino tableaux and certain pairs of ordinary tableaux of the same weight that together fill the same shape, and which determine the "plactic class" of the domino tableau; (2) a weight preserving reversible transformation of domino tableaux into ordinary tableaux of a related shape (the correspondence involves 2-quotients) mapping the subset of Yamanouchi domino tableaux onto that of the Littlewood-Richardson tableaux; (3) a correspondence between Yamanouchi domino tableaux of shape $\lambda$ and weight $\mu$ and Yamanouchi domino tableaux of shape $\mu'$ and weight $\lambda$, where $\mu'$ is $\mu$ scaled horizontally and vertically by a factor $2$. The essential properties of (1) and (2) are obtained by proving their commutation with the "coplactic" (or crystal) operations (which for domino tableaux were defined by Carré and Leclerc). Construction (2) allows algorithmic separation of the Littlewood-Richardson tableaux describing the decomposition of the tensor square of a general linear group representation into contributions to its symmetric and alternating parts.
Improving Dense Packings of Equal Disks in a Square
Authors: Boll David W. , Donovan Jerry , Graham Ronald L. , Lubachevsky Boris D.
Published: January 2020

We describe a new numerical procedure for generating dense packings of disks and spheres inside various geometric shapes. We believe that in some of the smaller cases, these packings are in fact optimal. When applied to the previously studied cases of packing $n$ equal disks in a square, the procedure confirms all the previous record packings [NO1] [NO2] [GL], except for $n =$ 32, 37, 48, and 50 disks, where better packings than those previously recorded are found. For $n =$ 32 and 48, the new packings are minor variations of the previous record packings. However, for $n =$ 37 and 50, the new patterns differ substantially. For example, they are mirror-symmetric, while the previous record packings are not.
A Ramsey Treatment of Symmetry
Authors: Banakh T. , Verbitsky O. , Vorobets Ya.
Published: January 2020

Given a space $\Omega$ endowed with symmetry, we define $ms(\Omega, r)$ to be the maximum of $m$ such that for any $r$-coloring of $\Omega$ there exists a monochromatic symmetric set of size at least $m$. We consider a wide range of spaces $\Omega$ including the discrete and continuous segments $\{1, \ldots, n\}$ and $[0,1]$ with central symmetry, geometric figures with the usual symmetries of Euclidean space, and Abelian groups with a natural notion of central symmetry. We observe that $ms(\{1, \ldots, n\}, r)$ and $ms([0,1], r)$ are closely related, prove lower and upper bounds for $ms([0,1], 2)$, and find asymptotics of $ms([0,1], r)$ for $r$ increasing. The exact value of $ms(\Omega, r)$ is determined for figures of revolution, regular polygons, and multi-dimensional parallelopipeds. We also discuss problems of a slightly different flavor and, in particular, prove that the minimal $r$ such that there exists an $r$-coloring of the $k$-dimensional integer grid without infinite monochromatic symmetric subsets is $k+1$.
The Arc-Width of a Graph
Authors: Barát János , Hajnal Péter
Published: January 2020

The arc-representation of a graph is a mapping from the set of vertices to the arcs of a circle such that adjacent vertices are mapped to intersecting arcs. The width of such a representation is the maximum number of arcs having a point in common. The arc-width ($aw$) of a graph is the minimum width of its arc-representations. We show how arc-width is related to path-width and vortex-width. We prove that $aw(K_{s,s})=s$.
General Bounds for Identifying Codes in Some Infinite Regular Graphs
Authors: Charon Irène , Honkala Iiro , Hudry Olivier , Lobstein Antoine
Published: January 2020

Consider a connected undirected graph $G=(V,E)$ and a subset of vertices $C$. If for all vertices $v \in V$, the sets $B_r(v) \cap C$ are all nonempty and pairwise distinct, where $B_r(v)$ denotes the set of all points within distance $r$ from $v$, then we call $C$ an $r$-identifying code. We give general lower and upper bounds on the best possible density of $r$-identifying codes in three infinite regular graphs.
How Berger, Felzenbaum and Fraenkel Revolutionized Covering Systems the Same Way that George Boole Revolutionized Logic
Authors: Zeilberger Doron
Published: January 2020

The Berger-Felzenbaum-Fraenkel approach to Covering Systems is exposited. In particular their gorgeous proof of the famous $a_n=a_{n-1}$ theorem for exact covering systems (found independently by Jamie Simpson), is reviewed, and the analogy of their approach to Boolean tautologies in Disjunctive Normal Form is pointed out.
Holes in Graphs
Authors: Peng Yuejian , Rödl Vojtech , Ruciński Andrzej
Published: January 2020

The celebrated Regularity Lemma of Szemerédi asserts that every sufficiently large graph $G$ can be partitioned in such a way that most pairs of the partition sets span $\epsilon$-regular subgraphs. In applications, however, the graph $G$ has to be dense and the partition sets are typically very small. If only one $\epsilon$-regular pair is needed, a much bigger one can be found, even if the original graph is sparse. In this paper we show that every graph with density $d$ contains a large, relatively dense $\epsilon$-regular pair. We mainly focus on a related concept of an $(\epsilon,\sigma)$-dense pair, for which our bound is, up to a constant, best possible.
On the Dimer Problem and the Ising Problem in Finite 3-dimensional Lattices
Authors: Loebl Martin
Published: January 2020

We present a new expression for the partition function of the dimer arrangements and the Ising partition function of the 3-dimensional cubic lattice. We use the Pfaffian method. The partition functions are expressed by means of expectations of determinants and Pfaffians of matrices associated with the cubic lattice.
Map Genus, Forbidden Maps, and Monadic Second-Order Logic
Authors: Courcelle B. , Dussaux V.
Published: January 2020

A map is a graph equipped with a circular order of edges around each vertex. These circular orders represent local planar embeddings. The genus of a map is the minimal genus of an orientable surface in which it can be embedded. The maps of genus at most $g$ are characterized by finitely many forbidden maps, relatively to an appropriate ordering related to the minor ordering of graphs. This yields a "noninformative" characterization of these maps, that is expressible in monadic second-order logic. We give another one, which is more informative in the sense that it specifies the relevant surface embedding, in addition to stating its existence.
Ternary Constant Weight Codes
Authors: Östergård Patric R. J. , Svanström Mattias
Published: January 2020

Let $A_3(n,d,w)$ denote the maximum cardinality of a ternary code with length $n$, minimum distance $d$, and constant Hamming weight $w$. Methods for proving upper and lower bounds on $A_3(n,d,w)$ are presented, and a table of exact values and bounds in the range $n \leq 10$ is given.
A $q$-Analogue of de Finetti's Theorem
Authors: Gnedin Alexander , Olshanski Grigori
Published: January 2020

A $q$-analogue of de Finetti's theorem is obtained in terms of a boundary problem for the $q$-Pascal graph. For $q$ a power of prime this leads to a characterisation of random spaces over the Galois field ${\Bbb F}_q$ that are invariant under the natural action of the infinite group of invertible matrices with coefficients from ${\Bbb F}_q$.
Pattern Avoidance in Permutations: Linear and Cyclic Orders
Authors: Vella Antoine
Published: January 2020

We generalize the notion of pattern avoidance to arbitrary functions on ordered sets, and consider specifically three scenarios for permutations: linear, cyclic and hybrid, the first one corresponding to classical permutation avoidance. The cyclic modification allows for circular shifts in the entries. Using two bijections, both ascribable to both Deutsch and Krattenthaler independently, we single out two geometrically significant classes of Dyck paths that correspond to two instances of simultaneous avoidance in the purely linear case, and to two distinct patterns in the hybrid case: non-decreasing Dyck paths (first considered by Barcucci et al.), and Dyck paths with at most one long vertical or horizontal edge. We derive a generating function counting Dyck paths by their number of low and high peaks, long horizontal and vertical edges, and what we call sinking steps. This translates into the joint distribution of fixed points, excedances, deficiencies, descents and inverse descents over 321-avoiding permutations. In particular we give an explicit formula for the number of 321-avoiding permutations with precisely $k$ descents, a problem recently brought up by Reifegerste. In both the hybrid and purely cyclic scenarios, we deal with the avoidance enumeration problem for all patterns of length up to 4. Simple Dyck paths also have a connection to the purely cyclic case; here the orbit-counting lemma gives a formula involving the Euler totient function and leads us to consider an interesting subgroup of the symmetric group.
Maximum Multiplicity of a Root of the Matching Polynomial of a Tree and Minimum Path Cover
Authors: Ku Cheng Yeaw , Wong K. B.
Published: January 2020

We give a necessary and sufficient condition for the maximum multiplicity of a root of the matching polynomial of a tree to be equal to the minimum number of vertex disjoint paths needed to cover it.
A $p,q$-analogue of a Formula of Frobenius
Authors: Briggs Karen S. , Remmel Jeffrey B.
Published: January 2020

Garsia and Remmel (JCT. A 41 (1986), 246-275) used rook configurations to give a combinatorial interpretation to the $q$-analogue of a formula of Frobenius relating the Stirling numbers of the second kind to the Eulerian polynomials. Later, Remmel and Wachs defined generalized $p,q$-Stirling numbers of the first and second kind in terms of rook placements. Additionally, they extended their definition to give a $p,q$-analogue of rook numbers for arbitrary Ferrers boards. In this paper, we use Remmel and Wach's definition and an extension of Garsia and Remmel's proof to give a combinatorial interpretation to a $p,q$-analogue of a formula of Frobenius relating the $p,q$-Stirling numbers of the second kind to the trivariate distribution of the descent number, major index, and comajor index over $S_n$. We further define a $p,q$-analogue of the hit numbers, and show analytically that for Ferrers boards, the $p,q$-hit numbers are polynomials in $(p,q)$ with nonnegative coefficients.
Finite Rogers-Ramanujan Type Identities
Authors: Sills Andrew V.
Published: January 2020

Polynomial generalizations of all 130 of the identities in Slater's list of identities of the Rogers-Ramanujan type are presented. Furthermore, duality relationships among many of the identities are derived. Some of the these polynomial identities were previously known but many are new. The author has implemented much of the finitization process in a Maple package which is available for free download from the author's website.