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In this short paper, generally, we define a family of functions fk depends on the Eisenstein series with weight 2k, for k ( N. More detail, by considering the function fk, we define a derivative formula for generating weakly modular forms with weight 12. As a result for this, we claim that this formula gives an advantage to find the special solutions of some differential equations.

In this paper, we point out that the proof of Theorem 2.4(5), Proposition 2.6(1) and Proposition 2.8(1) in the paper titled ?On (L,M)-fuzzy convex structures? (Filomat 33(13): 4151-4163, 2019) are not true in general. Then, we give three correct proofs of these results

In this paper the Alexandroff one point compactification of the 2-dimensional Khalimsky (K-, for brevity) plane (resp. the 1-dimensional Khalimsky line) is called the infinite K-sphere (resp. the infinite K-circle). The present paper initially proves that the infinite K-circle has the fixed point property (FPP, for short) in the set Con(Z*), where Con(Z*) means the set of all continuous self-maps f of the infinite K-circle. Next, we address the following query which remains open: Under what condition does the infinite K-sphere have the FPP? Regarding this issue, we prove that the infinite K-sphere has the FPP in the set Con*((Z2)*) (see Definition 1.1). Finally, we compare the FPP of the infinite K-sphere and that of the infinite M-sphere, where the infinite M-sphere means the one point compactification of the Marcus-Wyse topological plane.

The present paper studies certain low-level separation axioms of a topological space, denoted by A(X), induced by a geometric AC-complex X. After proving that whereas A(X) is an Alexandroff space satisfying the semi-T1 2 -separation axiom, we observe that it does neither satisfy the pre T1 2 -separation axiom nor is a Hausdorff space. These are main motivations of the present work. Although not every A(X) is a semi-T1 space, after proceeding with an edge to edge tiling (or a face to face crystallization) of Rn, n ? N, denoted by T(Rn) as an AC complex, we prove that A(T(Rn)) is a semi-T1 space. Furthermore, we prove that A(En), induced by an nD Cartesian AC complex Cn = (En,N,dim), is also a semi-T1 space, n ? N. The paper deals with AC-complexes with the locally finite (LF-, for brevity) property, which can be used in the fields of pure and applied mathematics as well as digital topology, computational topology, and digital geometry.

In this paper, we introduce some new notions such as interval valued neutrosophic soft points, interval valued neutrosophic soft mappings, interval valued neutrosophic soft Hausdorff topological spaces, and interval valued neutrosophic soft compact topological spaces. Cantor?s intersection theorem is proved for interval valued neutrosophic soft sets. The aim of this paper is to establish the existence of fixed points of interval valued neutrosophic soft mappings on interval valued neutrosophic soft compact topological spaces. Some examples are provided to support the concepts and the results presented herein.

In this paper, we consider a class of generalized operator equilibrium problems and derive a Minty type lemma for this class of problems. Further, we establish some existence theorems for the generalized operator equilibrium problems. The theorems presented in this paper generalize and unify many well-known results in the literature.

The present paper studies several types of compatible adjacency relations for digital products such as a $C$-compatible adjacency (or the $L_C$-property in \cite{H13}), an $S$-compatible adjacency in \cite{H19} (or the $L_S$-property in \cite{H13}), which can contribute to the study of product properties of digital spaces (or digital images). Furthermore, to study an automorphism group of a Cartesian product of two digital coverings which do not satisfy a radius $2$ local isomorphism, which remains open, the paper uses some properties of an ultra regular covering in \cite{H16}. By using this approach, we can substantially classify digital products. In particular, using a $C$-compatible adjacency (or the $L_C$-property), we address a product problem of a digital isomorphism (see Theorems 3.6 and 4.1).

The paper aims to propose the fixed point property(FPP for short) of smallest open neighborhoods of the n-dimensional Khalimsky space and further, the FPP of a Khalimsky (K-, for short) retract. Let (X, knX) be an n-dimensional Khalimsky topological space induced by the n-dimensional Khalimsky space denoted by (Zn, kn). Although not every connected Khalimsky topological space (X, knX) has the FPP, we prove that for every point x 2 Zn the smallest open K-topological neighborhood of x, denoted by SNK(x) ? (Zn,kn), has the FPP. Besides, the present paper also studies the almost fixed point property (AFPP, for brevity) of a K-topological space. In this paper all spaces (X,knX):= X are assumed to be connected and ?X? ? 2.

Up to now there is no homotopy for Marcus-Wyse (for short $M$-) topological spaces. In relation to the development of a homotopy for the category of Marcus-Wyse (for short $M$-) topological spaces on ${\bf Z}^2$, we need to generalize the $M$-topology on ${\bf Z}^2$ to higher dimensional spaces $X \subset {\bf Z}^n$, $n \geq 3$ \cite{HL1}. Hence the present paper establishes a new topology on ${\bf Z}^n, n \in {\bf N}$, where ${\bf N}$ is the set of natural numbers. It is called the {\it generalized Marcus-Wyse} (for short $H$-) topology and is denoted by $({\bf Z}^n, \gamma^n)$. Besides, we prove that $({\bf Z}^3, \gamma^3)$ induces only $6$- or $18$-adjacency relations. Namely, $({\bf Z}^3, \gamma^3)$ does not support a $26$-adjacency, which is quite different from the Khalimsky topology for $3$D digital spaces. After developing an $H$-adjacency induced by the connectedness of $({\bf Z}^n, \gamma^n)$, the present paper establishes topological graphs based on the $H$-topology, which is called an $HA$-space in the paper, so that we can establish a category of $HA$-spaces. By using the $H$-adjacency, we propose an $H$-topological graph homomorphism (for short $HA$-map) and an $HA$-isomorphism. Besides, we prove that an $HA$-map ({\it resp.} an $HA$-isomorphism) is broader than an $H$-continuous map ({\it resp.} an $H$-homeomorphism) and is an $H$-connectedness preserving map. Finally, after investigating some properties of an $HA$-isomorphism, we propose both an $HA$-retract and an extension problem of an $HA$-map for studying $HA$-spaces.

In this paper, we present some results on the complete convergence for arrays of rowwise negatively superadditive dependent (NSD, in short) random variables by using the Rosenthal-type maximal inequality, Kolmogorov exponential inequality and the truncation method. The results obtained in the paper extend the corresponding ones for weighted sums of negatively associated random variables with identical distribution to the case of arrays of rowwise NSD random variables without identical distribution.

In the paper under review, we analyze various types of degenerate abstract Volterra integrodifferential equations in sequentially complete locally convex spaces. From the theory of non-degenerate equations, it is well known that the class of (a,k)-regularized C-resolvent families provides an efficient tool for dealing with abstract Volterra integro-differential equations of scalar type. Following the approach of T.-J. Xiao and J. Liang [41]-[43], we introduce the class of degenerate exponentially equicontinuous (a,k)- regularized C-resolvent families and discuss its basic structural properties. In the final section of paper, we will look at generation of degenerate fractional resolvent operator families associated with abstract differential operators.

Using the concepts of a pair upclass, ?-admissible and ?-subadmissible mappings in this paper, are proven a coupled coincidence point results for mappings F : X2 ? X and g : X ? X. In this way, recent papers [27, 33] have been reformed and generalized. Two examples are given to support the theoretical results.

In this paper we study the geometry of relative superior Mandelbrot sets through S-iteration scheme. Our results are quit significant from other Mandelbrot sets existing in the literature. Besides this, we also observe that S-iteration scheme converges faster than Ishikawa iteration scheme. We believe that the results of this paper can be inspired thosewho are interested in creating automatically aesthetic patterns.

In this paper we survey the 3D reconstruction of an object from its 2D cross-sections has many applications in different fields of sciences such as medical physics and biomedical applications. The aim of this paper is to give not only the Bezier curves in medical applications, but also by using generating functions for the Bernstein basis functions and their identities, some combinatorial sums involving binomial coefficients are deriven. Finally, we give some comments related to the above areas.

The goal of the present paper is to study an extension problem of a connected preserving (for short, CP-) map between Khalimsky (K-for brevity, if there is no ambiguity) spaces. As a generalization of a K-continuous map, for K-topological spaces the recent paper [13] develops a function sending connected sets to connected ones (for brevity, an A-map: see Definition 3.1 in the present paper). Since this map plays an important role in applied topology including digital topology, digital geometry and mathematical morphology, the present paper studies an extension problem of a CP-map in terms of both an A-retract and an A-isomorphism (see Example 5.2). Since K-topological spaces have been often used for studying digital images, this extension problem can contribute to a certain areas of computer science and mathematical morphology.

Since a locally finite topological structure plays an important role in the fields of pure and applied topology, the paper studies a special kind of locally finite spaces, so called a space set topology (for brevity, SST) and further, proves that an SST is an Alexandroff space satisfying the separation axiom T0. Unlike a point set topology, since each element of an SST is a space, the present paper names the topology by the space set topology. Besides, for a connected topological space (X,T) with |X| = 2 the axioms T0, semi-T1/2 and T1/2 are proved to be equivalent to each other. Furthermore, the paper shows that an SST can be used for studying both continuous and digital spaces so that it plays a crucial role in both classical and digital topology, combinatorial, discrete and computational geometry. In addition, a connected SST can be a good example showing that the separation axiom semi-T1/2 does not imply T1/2.

In this paper, we show that the generalized Aluthge transformations of a large class of operators (weighted conditional type operators) are normal. As a consequence, the operatorMwEMu is p-hyponormal if and only if it is normal, and under a weak condition, if MwEMu is normal, then the Holder inequality turn into equality for w; u. Also, we give some applications of p-hyponormal weighted conditional type operators, for instance, point spectrum and joint point spectrum of p-hyponormal weighted conditional type operators are equal. In the end, some examples are provided to illustrate concrete application of the main results of the paper. This article has been retracted. Link to the retraction 10.2298/FIL1601253E

In this paper, new Hermite-Hadamard type inequalities for n-times differentiable log-preinvex functions are established. The established results generalize some of those results proved in recent papers for differentiable log-preinvex functions and differentiable log-convex functions.

The main objective of the paper is to prove some unified common fixed point theorems for a family of mappings under a minimal set of sufficient conditions. Our results subsume and improve a host of common fixed point theorems for contractive type mappings available in the literature of the metric fixed point theory. Simultaneously, we provide some new answers in a general framework to the problem posed by Rhoades (Contemp Math 72, 233-245, 1988) regarding the existence of a contractive definition which is strong enough to generate a fixed point, but which does not force the mapping to be continuous at the fixed point. Concrete examples are also given to illustrate the applicability of our proved results.

In this paper, the concept of weak KKM set-valued mapping is extended from topological vector spaces to hyperconvex metric spaces. For these mappings we obtain several intersection theorems that prove to be useful in establishing existence criteria for weak and strong solutions of the general variational inequality problem and minimax inequalities.

In this paper we introduce and study some new types of star-selection principles ((i,j)-NSM, (i,j)-NSR and (i,j)-NSH) in bitopologivcal spaces. Various properties of these selection properties are established and their relations with known selection principles are discussed. Several examples are given.

In this paper, one-weight and additive complementary dual (ACD) codes in Zr2 x Zs4 x Zt 8 are studied. Firstly, it is shown that the image of an equidistant Z2Z4Z8-additive code is a binary equidistant code. Then, some properties of the structure and possible weights for one-weight Z2Z4Z8-additive codes are described. Finally, it is given the sufficient conditions for a Z2Z4Z8-additive code to be ACD.

For a finite group G, let Z(G) denote the center of G and cs*(G) be the set of non-trivial conjugacy class sizes of G. In this paper, we show that if G is a finite group such that for some odd prime power q ? 4, cs*(G) = cs*(PGL2(q)), then either G ? PGL2(q) X Z(G) or G contains a normal subgroup N and a non-trivial element t ? G such that N ? PSL2(q)X Z(G), t2 ? N and G = N. ?t?. This shows that the almost simple groups cannot be determined by their set of conjugacy class sizes (up to an abelian direct factor).

In this paper, we investigate some conditions under which the action of an operator on a K-frame, remain again a K-frame for Hilbert module E. We also give a generalization of Douglas theorem to prove that the sum of two K-frames under certain condition is again a K-frame. Finally, we characterize the K-frame generators in terms of operators.

In this work, we examine the topology of special type of sequences in which each candidate is a polynomial with its coefficients are of integers taken from a discrete set. The paper develops a different perspective with regard to the recent progress in the theory of polynomials with bounded integer coefficients. In the context of discrete control systems, we apply the theory to one dimensional reachability problem of a convex polyhedra with finite number of controls acting on the system and prove that the reachable set of the discrete model is dense in the set of real numbers under the suitable finite control set.

The power graph P(G) of a group G is the graph with vertex set G and two distinct vertices are adjacent if one is a power of the other. Two finite groups are said to be conformal, if they contain the same number of elements of each order. Let Y be a family of all non-isomorphic odd order finite nilpotent groups of class two or p-groups of class less than p. In this paper, we prove that the power graph of each group in Y is isomorphic to the power graph of an abelian group and two groups in Y have isomorphic power graphs if they are conformal. We determine the number of maximal cyclic subgroups of a generalized extraspecial p-group (p odd) by determining the power graph of this group. We also determine the power graph of a p-group of order p4 (p odd).

In this paper, we establish fixed point theorems for generalized nonlinear contractive mappings using the concept of w-distance on metric spaces endowed with an arbitrary binary relation. Our fixed point theorems generalize recent results of Senapati and Dey [ J. Fixed Point Theory Appl., 19, 2945-2961, (2017)] and many other important results of the existing literature. Moreover, in order to revel the usability of our findings an example and an application to first order periodic boundary value problem are given.

In this paper elementary generalized systems of Boolean equations are investigated. The formula for solving systems of k Boolean inequations and a Boolean equation is presented. This systems have many applications in computer science for solving logical problems. Presented formulas can accelerate application of elementary generalized systems of Boolean equations.

In this paper, we consider the constraint set K := {x ? Rn : gj(x)? 0,? j = 1,2,...,m} of inequalities with nonsmooth nonconvex constraint functions gj : Rn ? R (j = 1,2,...,m).We show that under Abadie?s constraint qualification the ?perturbation property? of the best approximation to any x in Rn from a convex set ?K := C ? K is characterized by the strong conical hull intersection property (strong CHIP) of C and K, where C is an arbitrary non-empty closed convex subset of Rn: By using the idea of tangential subdifferential and a non-smooth version of Abadie?s constraint qualification, we do this by first proving a dual cone characterization of the constraint set K. Moreover, we present sufficient conditions for which the strong CHIP property holds. In particular, when the set ?K is closed and convex, we show that the Lagrange multiplier characterizations of constrained best approximation holds under a non-smooth version of Abadie?s constraint qualification. The obtained results extend many corresponding results in the context of constrained best approximation. Several examples are provided to clarify the results.

Given a graph H, a graphic sequence ? is potentially H-graphic if there is a realization of ? containing H as a subgraph. In 1991, Erd?s et al. introduced the following problem: determine the minimum even integer ?(H,n) such that each n-term graphic sequence with sum at least ?(H,n) is potentially H-graphic. This problem can be viewed as a ?potential? degree sequence relaxation of the Tur?n problems. Let H be an arbitrary graph of order k. Ferrara et al. [Combinatorica, 36(2016)687-702] established an upper bound on ?(H,n): if ? = ?(n) is an increasing function that tends to infinity with n, then there exists an N = N(?,H) such that ?(H,n)? ?~(H)n + ?(n) for any n ? N, where ?~(H) is a parameter only depending on the graph H. Recently, Yin [European J. Combin., 85(2020)103061] obtained a new upper bound on ?(H,n): there exists an M = M(k,?(H)) such that ?(H,n) ? ?~(H)n + k2-3k+4 for any n ? M. In this paper, we investigate the precise behavior of ?(H,n) for arbitrary H with ?~?(H)+1(H < ?~(H) or??(H)+1(H) ? 2, where ??(H)+1(H) = min{?F)|F is an induced subgraph of H and |V(F)|= ?(H) + 1} and ?~?(H)+1(H) = 2(k-?(H)-1)+??(H)+1(H)-1. Moreover, we also show that ?(H,n) = (k-?(H)-1)(2n-k+?(H))+2 for those H so that ??(H)+1(H) = 1,?~?(H)+1(H)=~?~(H),?~p(H) < ?~(H) for ?(H) + 2 ? p ? k and there is an F < H with |V(F)| = ?(H) + 1 and ?(F) = (12,0?(H)-1).

It is known that every digital covering map p:(E,k) ? (B,?) has the unique path lifting property. In this paper, we show that its inverse is true when the continuous surjective map p has no conciliator point. Also, we prove that a digital (k,?)-continuous surjection p:(E,k)? (B,?) is a digital covering map if and only if it is a local isomorphism, when all digital spaces are connected. Moreover, we find out a loop criterion for a digital covering map to be a radius n covering map.

The main aim of the paper is to give the crossing number of the join product G* + Dn for the connected graph G* of order six consisting of P4 + D1 and of one leaf incident with some inner vertex of the path P4 on four vertices, and where Dn consists of n isolated vertices. In the proofs, it will be extend the idea of the minimum numbers of crossings between two different subgraphs from the set of subgraphs which do not cross the edges of the graph G* onto the set of subgraphs by which the edges of G* are crossed exactly once. Due to the mentioned algebraic topological approach, we are able to extend known results concerning crossing numbers for join products of new graphs. The proofs are done with the help of software that generates all cyclic permutations for a given number k, and creates a new graph COG for calculating the distances between all (k-1)! vertices of the graph. Finally, by adding one edge to the graph G*, we are able to obtain the crossing number of the join product of one other graph with the discrete graph Dn.

In this paper, we consider several equivalent formulas for the distances from B? functions to F(p,q,s) space.

In this paper we consider the generalized Fibonacci numbers Fn,m and the generalized Lucas numbers Ln,m. Also, we introduce new sequences of numbers An,m, Bn,m, Cn,m and Dn,m. Further, we find the generating functions and some recurrence relations for these sequences of numbers.

In this paper, we present some interrelations among some restricted and unrestricted partitions of integers. Mainly, we derive new effective formulas for the partition function and compare our partition formula with well known recurrence formulas. Moreover, as the number increase, we observe how effective the new recurance formulas are.

A realizable degree sequence can be realized in many ways as a graph. There are several tests for determining realizability of a degree sequence. Up to now, not much was known about the common properties of these realizations. Euler characteristic is a well-known characteristic of graphs and their underlying surfaces. It is used to determine several combinatorial properties of a surface and of all graphs embedded onto it. Recently, last two authors defined a number ? which is invariant for all realizations of a given degree sequence. ? is shown to be related to Euler characteristic and cyclomatic number. Several properties of ? are obtained and some applications in extremal graph theory are done by authors. As already shown, the number gives direct information compared with the Euler characteristic on the realizability, number of realizations, being acyclic or cyclic, number of components, chords, loops, pendant edges, faces, bridges etc. In this paper, another important topological property of graphs which is connectedness is studied by means of ?. It is shown that all graphs with ?(G)?-4 are disconnected, and if ?(G)? -2, then the graph could be connected or disconnected. It is also shown that if the realization is a connected graph and ?(G)=-2, then certainly the graph should be acyclic. Similarly, it is shown that if the realization is a connected graph G and ?(G)? 0, then certainly the graph should be cyclic. Also, the fact that when ?(G)?-4, the components of the disconnected graph could not all be cyclic, and that if all the components of a graph G are cyclic, then ?(G) ? 0 are proven.

In data transmission networks, the feasibility of data transmission can be characterized by the existence of fractional factors. If some channels and stations are not available in the transmission network at the moment, the possibility of transmission between data is characterized by whether the corresponding graph structure of the network is critical deleted. Toughness used to measure the vulnerability and robustness of a network, which is an important parameter to be considered in network designing. In this paper, we mainly study the relationship between toughness and the all fractional critical deleted graph, and a toughness condition for a graph to be all fractional (g,f,n)-critical deleted is determined.

This paper defines a new class of L-fuzzy sets called r-L-fuzzy biconvex sets in (L,M)-fuzzy convex structures (X,C), where C is an (L,M)-fuzzy convexity on X, and some of their properties were studied. In addition, weintroduce (L,M)-fuzzy topological convexity space and study some of its properties. Finally, we introduce locally (L,M)-fuzzy topology (L,M)-fuzzy convexity space and study some of its properties.

Graphs whose spectrum belongs to the interval [-2,2] are called Smith graphs. The structure of a Smith graph with a given spectrum depends on a system of Diophantine linear algebraic equations. We have established in [1] several properties of this system and showed how it can be simplified and effectively applied. In this way a spectral theory of Smith graphs has been outlined. In the present paper we introduce cospectrality graphs for Smith graphs and study their properties through examples and theoretical consideration. The new notion is used in proving theorems on cospectrality of Smith graphs. In this way one can avoid the use of the mentioned system of Diophantine linear algebraic equations.

In this paper we define the m-extension of Fibonacci and Lucas p-difference sequences by using the m-extension of Fibonacci and Lucas p-numbers. We investigate some properties of our new sequences and introduce some relations between the m-extension of Fibonacci and Lucas p-difference sequences and the m-extension of Fibonacci and Lucas p-numbers. Moreover, we present the sums and generating function of the m-extension of Fibonacci and Lucas p-difference sequences. Finally, we study the m-extension of Fibonacci p-difference Newton polynomial interpolation.

In this paper, the concept partial S-metric space is introduced as a generalization of S-metric space. We prove certain coincidence point theorems in partial S-metric spaces. The results we obtain generalize many known results in fixed point theory. Also, some examples show the e_ectiveness of this approach.

In this paper, we define the multiparameter r-Whitney numbers of the first and second kind. The recurrence relations, generating functions , explicit formulas of these numbers and some combinatorial identities are derived. Some relations between these numbers and generalized Stirling numbers of the first and second kind, Lah numbers, C-numbers and harmonic numbers are deduced. Furthermore, some interesting special cases are given. Finally matrix representation for these relations are given.

Since Molodtsov defined the concept of soft sets, many types of soft equality relations between two soft sets were discussed. Amongthese types are 1-soft equality and gf-soft equality relations introduced in [1] and [2], respectively. In this paper, we first aim to show that some results obtained in [1,2] need not be true, by giving two counterexamples. Second, we investigate under what conditions these results are correct. Finally, we define and study the concepts of gf-soft union and gf-soft intersection for arbitrary family of soft sets.

8th International Conference on Mathematical Analysis, Differential Equation and Applications (MADEA) -- JUN 17-23, 2018 -- Cholpon Ata, KYRGYZSTAN WOS: 000496192400014 In this paper we study some new sequence spaces of strongly lacunary almost summable sequences, which naturally come up for investigation and which will fill up a gap in the existing literature. Some topological results, a characterization of strongly lacunary almost regular matrices, uniqueness of generalized limits and inclusion relations of such sequences have been observed. Kyrgyz Turkish Manas Univ, Mersin Univ, NAS Ukraine, Inst Math, Taras Shevchenko Natl Univ Kyiv

In this paper, the notion of (L,M)-fuzzy topological-convex spaces is introduced and some of its characterizations are obtained. Then the notion of (L,M)-fuzzy convex enclosed relation spaces is introduced and its one-to-one correspondence with (L,M)-fuzzy convex space is studied. Based on this, the notion of (L,M)-fuzzy topological-convex enclosed relation spaces is introduced and its categorical isomorphism to (L,M)-fuzzy topological-convex spaces is discussed.

In this paper we obtain an approximation of the block numerical range of bounded and unbounded block operator matrices by projection methods.

The double-orbit graph is a generalization of vertex transitive graphs, which contains many classic network models. Conditional edge-connectivity is an important index to measure the fault-tolerance and reliability of the networks. In this paper, we characterize the super-?(2) double-orbit graphs with two orbits of the same size. Moreover, we give a sufficient condition for regular double-orbit graphs to be ?(3)-optimal, and characterize super- ?(3) regular double-orbit graphs.

In this paper, using the concept of w-distance on a metric space, we prove some new best proximity point results for the mappings of Meir-Keeler type. As an application, we derive some recent best proximity point results of the aforementioned type.

A non-increasing sequence ? = (d1,. . ., dn) of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices. In this case, G is referred to as a realization of ?. Given a graph H, a graphic sequence ? is potentially H-graphic if ? has a realization containing H as a subgraph. Busch et al. (Graphs Combin., 30(2014)847-859) considered a degree sequence analogue to classical graph Ramsey number as follows: for graphs G1 and G2, the potential-Ramsey number rpot(G1,G2) is the smallest non-negative integer k such that for any k-term graphic sequence ?, either ? is potentially G1-graphic or the complementary sequence ? = (k - 1 - dk,..., k - 1 - d1) is potentially G2-graphic. They also gave a lower bound on rpot(G;Kr+1) for a number of choices of G and determined the exact values for rpot(Kn;Kr+1), rpot(Cn;Kr+1) and rpot(Pn,Kr+1). In this paper, we will extend the complete graph Kr+1 to the complete split graph Sr,s = Kr ? Ks. Clearly, Sr,1 = Kr+1. We first give a lower bound on rpot(G, Sr,s) for a number of choices of G, and then determine the exact values for rpot(Cn, Sr,s) and rpot(Pn, Sr,s).

Let $(X,\tau)$ be a Hausdorff space, where $X$ is an infinite set. The compact complement topology $\tau^{\star}$ on $X$ is defined by: $\tau^{\star}=\{\emptyset\} \cup \{X\setminus M, \text{where $M$ is compact in $(X,\tau)$}\}$. In this paper, properties of the space $(X, \tau^{\star})$ are studied in $\mathbf{ZF}$ and applied to a characterization of $k$-spaces, to the Sorgenfrey line, to some statements independent of $\mathbf{ZF}$, as well as to partial topologies that are among Delfs-Knebusch generalized topologies. Among other results, it is proved that the axiom of countable multiple choice (\textbf{CMC}) is equivalent with each of the following two sentences: (i) every Hausdorff first countable space is a $k$-space, (ii) every metrizable space is a $k$-space. A \textbf{ZF}-example of a countable metrizable space whose compact complement topology is not first countable is given.