Pub Date : 2024-09-13DOI: 10.1017/s0004972724000534
YUCHEN DING
Let $mathcal {P}$ be the set of primes and $pi (x)$ the number of primes not exceeding x. Let $P^+(n)$ be the largest prime factor of n, with the convention $P^+(1)=1$, and $ T_c(x)=#{ple x:pin mathcal {P},P^+(p-1)ge p^c}. $ Motivated by a conjecture of Chen and Chen [‘On the largest prime factor of shifted primes’, Acta Math. Sin. (Engl. Ser.)33 (2017), 377–382], we show that for any c with $8/9le c<1$, $$ begin{align*} limsup_{xrightarrowinfty}T_c(x)/pi(x)le 8(1/c-1), end{align*} $$
which clearly means that $$ begin{align*} limsup_{xrightarrowinfty}T_c(x)/pi(x)rightarrow 0 quad text{as } crightarrow 1. end{align*} $$
{"title":"ON A CONJECTURE ON SHIFTED PRIMES WITH LARGE PRIME FACTORS, II","authors":"YUCHEN DING","doi":"10.1017/s0004972724000534","DOIUrl":"https://doi.org/10.1017/s0004972724000534","url":null,"abstract":"<p>Let <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$mathcal {P}$</span></span></img></span></span> be the set of primes and <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$pi (x)$</span></span></img></span></span> the number of primes not exceeding <span>x</span>. Let <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$P^+(n)$</span></span></img></span></span> be the largest prime factor of <span>n</span>, with the convention <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$P^+(1)=1$</span></span></img></span></span>, and <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline5.png\"><span data-mathjax-type=\"texmath\"><span>$ T_c(x)=#{ple x:pin mathcal {P},P^+(p-1)ge p^c}. $</span></span></img></span></span> Motivated by a conjecture of Chen and Chen [‘On the largest prime factor of shifted primes’, <span>Acta Math. Sin. (Engl. Ser.)</span> <span>33</span> (2017), 377–382], we show that for any <span>c</span> with <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$8/9le c<1$</span></span></img></span></span>, <span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_eqnu1.png\"><span data-mathjax-type=\"texmath\"><span>$$ begin{align*} limsup_{xrightarrowinfty}T_c(x)/pi(x)le 8(1/c-1), end{align*} $$</span></span></img></span></p><p>which clearly means that <span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912124419965-0789:S0004972724000534:S0004972724000534_eqnu2.png\"><span data-mathjax-type=\"texmath\"><span>$$ begin{align*} limsup_{xrightarrowinfty}T_c(x)/pi(x)rightarrow 0 quad text{as } crightarrow 1. end{align*} $$</span></span></img></span></p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"75 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000510
LENNY JONES
A monic polynomial $f(x)in {mathbb Z}[x]$ of degree N is called monogenic if $f(x)$ is irreducible over ${mathbb Q}$ and ${1,theta ,theta ^2,ldots ,theta ^{N-1}}$ is a basis for the ring of integers of ${mathbb Q}(theta )$, where $f(theta )=0$. We prove that there exist exactly three distinct monogenic trinomials of the form $x^4+bx^2+d$ whose Galois group is the cyclic group of order 4. We also show that the situation is quite different when the Galois group is not cyclic.
{"title":"MONOGENIC EVEN QUARTIC TRINOMIALS","authors":"LENNY JONES","doi":"10.1017/s0004972724000510","DOIUrl":"https://doi.org/10.1017/s0004972724000510","url":null,"abstract":"<p>A monic polynomial <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$f(x)in {mathbb Z}[x]$</span></span></img></span></span> of degree <span>N</span> is called <span>monogenic</span> if <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$f(x)$</span></span></img></span></span> is irreducible over <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline3.png\"><span data-mathjax-type=\"texmath\"><span>${mathbb Q}$</span></span></img></span></span> and <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline4.png\"><span data-mathjax-type=\"texmath\"><span>${1,theta ,theta ^2,ldots ,theta ^{N-1}}$</span></span></img></span></span> is a basis for the ring of integers of <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline5.png\"><span data-mathjax-type=\"texmath\"><span>${mathbb Q}(theta )$</span></span></img></span></span>, where <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$f(theta )=0$</span></span></img></span></span>. We prove that there exist exactly three distinct monogenic trinomials of the form <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125559562-0272:S0004972724000510:S0004972724000510_inline7.png\"><span data-mathjax-type=\"texmath\"><span>$x^4+bx^2+d$</span></span></img></span></span> whose Galois group is the cyclic group of order 4. We also show that the situation is quite different when the Galois group is not cyclic.</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"65 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000492
RUI-JING WANG
For any positive integer n, let $sigma (n)$ be the sum of all positive divisors of n. We prove that for every integer k with $1leq kleq 29$ and $(k,30)=1,$$$ begin{align*} sum_{nleq K}sigma(30n)>sum_{nleq K}sigma(30n+k) end{align*} $$
for all $Kin mathbb {N},$ which gives a positive answer to a problem posed by Pongsriiam [‘Sums of divisors on arithmetic progressions’, Period. Math. Hungar. 88 (2024), 443–460].
对于任意正整数 n,让 $sigma (n)$ 是 n 的所有正除数之和。我们证明,对于每一个整数k,只要有$1leq kleq 29$和$(k,30)=1,$$ begin{align*}。sum_{nleq K}sigma(30n)>sum_{nleq K}sigma(30n+k) end{align*}$$for all $Kin mathbb {N}, $ 这给了 Pongsriiam 提出的问题一个肯定的答案['Sums of divisors on arithmetic progressions', Period.Math.匈牙利。88 (2024), 443-460].
{"title":"ON A PROBLEM OF PONGSRIIAM ON THE SUM OF DIVISORS","authors":"RUI-JING WANG","doi":"10.1017/s0004972724000492","DOIUrl":"https://doi.org/10.1017/s0004972724000492","url":null,"abstract":"<p>For any positive integer <span>n</span>, let <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240913031000660-0696:S0004972724000492:S0004972724000492_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$sigma (n)$</span></span></img></span></span> be the sum of all positive divisors of <span>n</span>. We prove that for every integer <span>k</span> with <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240913031000660-0696:S0004972724000492:S0004972724000492_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$1leq kleq 29$</span></span></img></span></span> and <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240913031000660-0696:S0004972724000492:S0004972724000492_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$(k,30)=1,$</span></span></img></span></span> <span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240913031000660-0696:S0004972724000492:S0004972724000492_eqnu1.png\"><span data-mathjax-type=\"texmath\"><span>$$ begin{align*} sum_{nleq K}sigma(30n)>sum_{nleq K}sigma(30n+k) end{align*} $$</span></span></img></span></p><p>for all <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240913031000660-0696:S0004972724000492:S0004972724000492_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$Kin mathbb {N},$</span></span></img></span></span> which gives a positive answer to a problem posed by Pongsriiam [‘Sums of divisors on arithmetic progressions’, <span>Period. Math. Hungar</span>. <span>88</span> (2024), 443–460].</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"6 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000480
MICHAEL COONS, JOHN LIND
We give a new proof of a theorem of Bell and Coons [‘Transcendence tests for Mahler functions’, Proc. Amer. Math. Soc.145(3) (2017), 1061–1070] on the leading order radial asymptotics of Mahler functions that are the generating functions of regular sequences. Our method allows us to provide a description of the oscillations whose existence was shown by Bell and Coons. This extends very recent results of Poulet and Rivoal [‘Radial behavior of Mahler functions’, Int. J. Number Theory, to appear].
{"title":"RADIAL ASYMPTOTICS OF GENERATING FUNCTIONS OF k-REGULAR SEQUENCES","authors":"MICHAEL COONS, JOHN LIND","doi":"10.1017/s0004972724000480","DOIUrl":"https://doi.org/10.1017/s0004972724000480","url":null,"abstract":"<p>We give a new proof of a theorem of Bell and Coons [‘Transcendence tests for Mahler functions’, <span>Proc. Amer. Math. Soc.</span> <span>145</span>(3) (2017), 1061–1070] on the leading order radial asymptotics of Mahler functions that are the generating functions of regular sequences. Our method allows us to provide a description of the oscillations whose existence was shown by Bell and Coons. This extends very recent results of Poulet and Rivoal [‘Radial behavior of Mahler functions’, <span>Int. J. Number Theory</span>, to appear].</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"37 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000522
LU CHEN, YUEYU WU
<p>A cycle <span>C</span> of a graph <span>G</span> is <span>dominating</span> if <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline1.png"><span data-mathjax-type="texmath"><span>$V(C)$</span></span></img></span></span> is a dominating set and <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline2.png"><span data-mathjax-type="texmath"><span>$V(G)backslash V(C)$</span></span></img></span></span> is an independent set. Wu <span>et al.</span> [‘Degree sums and dominating cycles’, <span>Discrete Mathematics</span> <span>344</span> (2021), Article no. 112224] proved that every longest cycle of a <span>k</span>-connected graph <span>G</span> on <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline3.png"><span data-mathjax-type="texmath"><span>$ngeq 3$</span></span></img></span></span> vertices with <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline4.png"><span data-mathjax-type="texmath"><span>$kgeq 2$</span></span></img></span></span> is dominating if the degree sum is more than <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline5.png"><span data-mathjax-type="texmath"><span>$(k+1)(n+1)/3$</span></span></img></span></span> for any <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline6.png"><span data-mathjax-type="texmath"><span>$k+1$</span></span></img></span></span> pairwise nonadjacent vertices. They also showed that this bound is sharp. In this paper, we show that the extremal graphs <span>G</span> for this condition satisfy <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline7.png"><span data-mathjax-type="texmath"><span>$(n-2)/3K_1vee (n+1)/3K_2 subseteq G subseteq K_{(n-2)/3}vee (n+1)/3K_2$</span></span></img></span></span> or <span><span><img data-mimesubtype="png" data-type="" src="https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline8.png"><span data-mathjax-type="texmath"><span>$2K_1vee 3K_{(n-2)/3}subseteq G subseteq K_2vee 3K_{(n-2)/3}.$</span></sp
如果 $V(C)$ 是支配集且 $V(G)backslash V(C)$ 是独立集,那么图 G 的循环 C 就是支配集。Wu 等人['度和与支配循环',《离散数学》344 (2021),文章编号:112224]证明了每一个最长的循环都是支配循环。112224]证明了如果对于任意 $k+1$ 成对非相邻顶点的度数总和大于 $(k+1)(n+1)/3$,则在 $ngeq 3$ 顶点上具有 $kgeq 2$ 的 k 连接图 G 的每个最长循环都是支配循环。他们还证明了这一界限是尖锐的。在本文中,我们证明了这个条件下的极值图 G 满足 $(n-2)/3K_1vee (n+1)/3K_2 subseteq G subseteq K_{(n-2)/3}vee (n+1)/3K_2$ 或 $2K_1vee 3K_{(n-2)/3}subseteq G subseteq K_2vee 3K_{(n-2)/3}.$ 。
{"title":"EXTREMAL GRAPHS FOR DEGREE SUMS AND DOMINATING CYCLES","authors":"LU CHEN, YUEYU WU","doi":"10.1017/s0004972724000522","DOIUrl":"https://doi.org/10.1017/s0004972724000522","url":null,"abstract":"<p>A cycle <span>C</span> of a graph <span>G</span> is <span>dominating</span> if <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$V(C)$</span></span></img></span></span> is a dominating set and <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$V(G)backslash V(C)$</span></span></img></span></span> is an independent set. Wu <span>et al.</span> [‘Degree sums and dominating cycles’, <span>Discrete Mathematics</span> <span>344</span> (2021), Article no. 112224] proved that every longest cycle of a <span>k</span>-connected graph <span>G</span> on <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline3.png\"><span data-mathjax-type=\"texmath\"><span>$ngeq 3$</span></span></img></span></span> vertices with <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline4.png\"><span data-mathjax-type=\"texmath\"><span>$kgeq 2$</span></span></img></span></span> is dominating if the degree sum is more than <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline5.png\"><span data-mathjax-type=\"texmath\"><span>$(k+1)(n+1)/3$</span></span></img></span></span> for any <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline6.png\"><span data-mathjax-type=\"texmath\"><span>$k+1$</span></span></img></span></span> pairwise nonadjacent vertices. They also showed that this bound is sharp. In this paper, we show that the extremal graphs <span>G</span> for this condition satisfy <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline7.png\"><span data-mathjax-type=\"texmath\"><span>$(n-2)/3K_1vee (n+1)/3K_2 subseteq G subseteq K_{(n-2)/3}vee (n+1)/3K_2$</span></span></img></span></span> or <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125250921-0666:S0004972724000522:S0004972724000522_inline8.png\"><span data-mathjax-type=\"texmath\"><span>$2K_1vee 3K_{(n-2)/3}subseteq G subseteq K_2vee 3K_{(n-2)/3}.$</span></sp","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000509
JIE CHEN, SHOU-JUN XU
In an isolate-free graph G, a subset S of vertices is a semitotal dominating set of G if it is a dominating set of G and every vertex in S is within distance 2 of another vertex of S. The semitotal domination number of G, denoted by $gamma _{t2}(G)$, is the minimum cardinality of a semitotal dominating set in G. Goddard, Henning and McPillan [‘Semitotal domination in graphs’, Utilitas Math.94 (2014), 67–81] characterised the trees and graphs of minimum degree 2 with semitotal domination number half their order. In this paper, we characterise all graphs whose semitotal domination number is half their order.
在无孤立图 G 中,如果顶点子集 S 是 G 的支配集,且 S 中的每个顶点与 S 中另一个顶点的距离都在 2 以内,则该顶点子集 S 是 G 的半总支配集。G 的半总支配数用 $gamma _{t2}(G)$ 表示,是 G 中半总支配集的最小心性。Goddard、Henning 和 McPillan ['图中的半总支配数',Utilitas Math.在本文中,我们将描述所有半总支配数为其阶数一半的图的特征。
{"title":"GRAPHS WITH SEMITOTAL DOMINATION NUMBER HALF THEIR ORDER","authors":"JIE CHEN, SHOU-JUN XU","doi":"10.1017/s0004972724000509","DOIUrl":"https://doi.org/10.1017/s0004972724000509","url":null,"abstract":"<p>In an isolate-free graph <span>G</span>, a subset <span>S</span> of vertices is a <span>semitotal dominating set</span> of <span>G</span> if it is a dominating set of <span>G</span> and every vertex in <span>S</span> is within distance 2 of another vertex of <span>S</span>. The <span>semitotal domination number</span> of <span>G</span>, denoted by <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240912125800045-0875:S0004972724000509:S0004972724000509_inline1.png\"><span data-mathjax-type=\"texmath\"><span>$gamma _{t2}(G)$</span></span></img></span></span>, is the minimum cardinality of a semitotal dominating set in <span>G</span>. Goddard, Henning and McPillan [‘Semitotal domination in graphs’, <span>Utilitas Math.</span> <span>94</span> (2014), 67–81] characterised the trees and graphs of minimum degree 2 with semitotal domination number half their order. In this paper, we characterise all graphs whose semitotal domination number is half their order.</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"2 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1017/s0004972724000455
YUAN CHEN, NIAN HONG ZHOU
We establish some inequalities that arise from truncating Lerch sums and derive uniform asymptotic formulae for the spt-crank of ordinary partitions. The uniform asymptotic formulae improve upon a result of Mao [‘Asymptotic formulas for spt-crank of partitions’, J. Math. Anal. Appl.460(1) (2018), 121–139].
我们建立了截断勒奇和所产生的一些不等式,并推导出了普通分区 spt-rank的统一渐近公式。统一渐近公式改进了毛泽东的一个结果['Asymptotic formulas for spt-crank of partitions', J. Math.Anal.460(1) (2018),121-139]。
{"title":"INEQUALITIES AND UNIFORM ASYMPTOTIC FORMULAE FOR SPT-CRANK OF PARTITIONS","authors":"YUAN CHEN, NIAN HONG ZHOU","doi":"10.1017/s0004972724000455","DOIUrl":"https://doi.org/10.1017/s0004972724000455","url":null,"abstract":"<p>We establish some inequalities that arise from truncating Lerch sums and derive uniform asymptotic formulae for the spt-crank of ordinary partitions. The uniform asymptotic formulae improve upon a result of Mao [‘Asymptotic formulas for spt-crank of partitions’, <span>J. Math. Anal. Appl.</span> <span>460</span>(1) (2018), 121–139].</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"12 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1017/s0004972724000467
JI-CAI LIU, JING LIU
We establish a q-analogue of a supercongruence related to a supercongruence of Rodriguez-Villegas, which extends a q-congruence of Guo and Zeng [‘Some q-analogues of supercongruences of Rodriguez-Villegas’, J. Number Theory145 (2014), 301–316]. The important ingredients in the proof include Andrews’ $_4phi _3$ terminating identity.
我们建立了一个与罗德里格斯-维耶加斯的超等公差相关的 q-analogue ,它扩展了郭和曾的 q-ongruence ['罗德里格斯-维耶加斯的超等公差的一些 q-analogue', J. Number Theory145 (2014), 301-316] 。证明中的重要成分包括安德鲁斯的$_4phi _3$终止身份。
{"title":"A q-SUPERCONGRUENCE ARISING FROM ANDREWS’ IDENTITY","authors":"JI-CAI LIU, JING LIU","doi":"10.1017/s0004972724000467","DOIUrl":"https://doi.org/10.1017/s0004972724000467","url":null,"abstract":"We establish a <jats:italic>q</jats:italic>-analogue of a supercongruence related to a supercongruence of Rodriguez-Villegas, which extends a <jats:italic>q</jats:italic>-congruence of Guo and Zeng [‘Some <jats:italic>q</jats:italic>-analogues of supercongruences of Rodriguez-Villegas’, <jats:italic>J. Number Theory</jats:italic>145 (2014), 301–316]. The important ingredients in the proof include Andrews’ <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000467_inline2.png\"/> <jats:tex-math> $_4phi _3$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> terminating identity.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"2 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-27DOI: 10.1017/s0004972724000479
ELCHIN HASANALIZADE, POO-SUNG PARK
Let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline1.png"/> <jats:tex-math> $kgeq 4$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> be an integer. We prove that the set <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline2.png"/> <jats:tex-math> $mathcal {O}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> of all nonzero generalised octagonal numbers is a <jats:italic>k</jats:italic>-additive uniqueness set for the set of multiplicative functions. That is, if a multiplicative function <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline3.png"/> <jats:tex-math> $f_k$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> satisfies the condition <jats:disp-formula> <jats:alternatives> <jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_eqnu1.png"/> <jats:tex-math> $$ begin{align*} f_k(x_1+x_2+cdots+x_k)=f_k(x_1)+f_k(x_2)+cdots+f_k(x_k) end{align*} $$ </jats:tex-math> </jats:alternatives> </jats:disp-formula> for arbitrary <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline4.png"/> <jats:tex-math> $x_1,ldots ,x_kin mathcal {O}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, then <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline5.png"/> <jats:tex-math> $f_k$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is the identity function <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline6.png"/> <jats:tex-math> $f_k(n)=n$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> for all <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline7.png"/> <jats:tex-math> $nin mathbb {N}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. We also show that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline8.png"/> <jats:tex-math> $f_2$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> and <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="png" xlink:href="S0004972724000479_inline9.png"/> <jats:tex-math> $f_3$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> are not determined uniquel
让 $kgeq 4$ 是一个整数。我们证明所有非零广义八角数的集合 $mathcal {O}$ 是乘法函数集合的 k-additive uniqueness 集合。也就是说,如果一个乘法函数 $f_k$ 满足条件 $$ begin{align*} f_k(x_1+x_2+cdots+x_k)=f_k(x_1)+f_k(x_2)+cdots+f_k(x_k) end{align*}$$ for arbitrary $x_1,ldots ,x_kin mathcal {O}$ , then $f_k$ is the identity function $f_k(n)=n$ for all $nin mathbb {N}$.我们还证明 $f_2$ 和 $f_3$ 并不是唯一确定的。
{"title":"MULTIPLICATIVE FUNCTIONS k-ADDITIVE ON GENERALISED OCTAGONAL NUMBERS","authors":"ELCHIN HASANALIZADE, POO-SUNG PARK","doi":"10.1017/s0004972724000479","DOIUrl":"https://doi.org/10.1017/s0004972724000479","url":null,"abstract":"Let <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline1.png\"/> <jats:tex-math> $kgeq 4$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> be an integer. We prove that the set <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline2.png\"/> <jats:tex-math> $mathcal {O}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> of all nonzero generalised octagonal numbers is a <jats:italic>k</jats:italic>-additive uniqueness set for the set of multiplicative functions. That is, if a multiplicative function <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline3.png\"/> <jats:tex-math> $f_k$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> satisfies the condition <jats:disp-formula> <jats:alternatives> <jats:graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_eqnu1.png\"/> <jats:tex-math> $$ begin{align*} f_k(x_1+x_2+cdots+x_k)=f_k(x_1)+f_k(x_2)+cdots+f_k(x_k) end{align*} $$ </jats:tex-math> </jats:alternatives> </jats:disp-formula> for arbitrary <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline4.png\"/> <jats:tex-math> $x_1,ldots ,x_kin mathcal {O}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>, then <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline5.png\"/> <jats:tex-math> $f_k$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is the identity function <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline6.png\"/> <jats:tex-math> $f_k(n)=n$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> for all <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline7.png\"/> <jats:tex-math> $nin mathbb {N}$ </jats:tex-math> </jats:alternatives> </jats:inline-formula>. We also show that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline8.png\"/> <jats:tex-math> $f_2$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> and <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972724000479_inline9.png\"/> <jats:tex-math> $f_3$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> are not determined uniquel","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"2 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-27DOI: 10.1017/s0004972724000431
ARUSHI, GEETHA VENKATARAMAN
We find an upper bound for the number of groups of order n up to isomorphism in the variety ${mathfrak {S}}={mathfrak {A}_p}{mathfrak {A}_q}{mathfrak {A}_r}$, where p, q and r are distinct primes. We also find a bound on the orders and on the number of conjugacy classes of subgroups that are maximal amongst the subgroups of the general linear group that are also in the variety $mathfrak {A}_qmathfrak {A}_r$.
我们发现了在 ${mathfrak {S}}={mathfrak {A}_p}{mathfrak {A}_q}{mathfrak {A}_r}$ 变项(其中 p、q 和 r 是不同的素数)中阶数为 n 的同构群的数量上限。我们还找到了在一般线性群的子群中也在 $mathfrak {A}_qmathfrak {A}_r}$ 中的最大子群的阶数和共轭类数的约束。
{"title":"ENUMERATION OF GROUPS IN SOME SPECIAL VARIETIES OF A-GROUPS","authors":"ARUSHI, GEETHA VENKATARAMAN","doi":"10.1017/s0004972724000431","DOIUrl":"https://doi.org/10.1017/s0004972724000431","url":null,"abstract":"<p>We find an upper bound for the number of groups of order <span>n</span> up to isomorphism in the variety <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240824023521338-0591:S0004972724000431:S0004972724000431_inline1.png\"><span data-mathjax-type=\"texmath\"><span>${mathfrak {S}}={mathfrak {A}_p}{mathfrak {A}_q}{mathfrak {A}_r}$</span></span></img></span></span>, where <span>p</span>, <span>q</span> and <span>r</span> are distinct primes. We also find a bound on the orders and on the number of conjugacy classes of subgroups that are maximal amongst the subgroups of the general linear group that are also in the variety <span><span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240824023521338-0591:S0004972724000431:S0004972724000431_inline2.png\"><span data-mathjax-type=\"texmath\"><span>$mathfrak {A}_qmathfrak {A}_r$</span></span></img></span></span>.</p>","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"2012 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}