In this paper we show that it is consistent with ZFC that the cardinality of every maximal cofinitary group of Sym(ω) is strictly greater than the cardinal numbers d and a.

In this paper we shall be concerned with a certain particular problem from the general theory of sets, namely with the problem of the existence of families of mutually exclusive sets with a maximal power . It will turn out-in a rather unexpected way that the solution of these problems essentially involves the notion of the so-called "inaccessible numbers ." In this connection we shall make some...

We focus on L(A), the filter of supersets of A in the structure of the computably enumerable sets under the inclusion relation, where A is an atomless r-maximal set. We answer a long standing question by showing that there are infinitely many pairwise non-isomorphic filters of this type.

in this paper, using pre-semi-open l-sets and their inequality, a new notion of ps-compactness is introduced in l-topological spaces, where l is a complete de morgan algebra. this notion does not depend on the structure of the basis lattice l and l does not need any distributivity.

Let S ⊆ Zn satisfy the property that conv(S) ∩ Zn = S. Then a convex set K is called an S-free convex set if int(K) ∩ S = ∅. A maximal S-free convex set is an S-free convex set that is not properly contained in any S-free convex set. We show that maximal S-free convex sets are polyhedra. This result generalizes a result of Basu et al. [6] for the case where S is the set of integer points in a r...

For a set D of polyominoes, a packing of the plane with D is a maximal set of copies of polyominoes from D that are not overlapping. A packing with smallest density is called a clumsy packing. We give an example of a set D such that any clumsy packing is aperiodic. In addition, we compute the smallest possible density of a clumsy packing when D consists of a single polyomino of a given size and...

Let f be a polynomial endomorphism of degree d ≥ 2 of C k (k ≥ 2) which extends to a holomorphic endomorphism of P k. Assume that the maximal order Julia set of f is laminated by real hypersurfaces in some open set. We show that f is homogenous and is a polynomial lift of a Lattès endomorphism of P k−1 .

We consider the possible cardinalities of the following three cardinal invariants which are related to the permutation group on the set of natural numbers: ag := the least cardinal number of maximal cofinitary permutation groups; ap := the least cardinal number of maximal almost disjoint permutation families; c(Sym(N)) := the cofinality of the permutation group on the set of natural numbers. We...

We give an 0 (nlogln) [ime algorirnm for finding a minimum independem dominating se[ in a pennmation graph. TItis improves on ilie previous D(n 3) time algorictun known for solving tllis problem [4]. .,. Dept of CompUlcr Sci., Purdue Univ., West Gf:tyelle, IN 47907. Rcso::trch ~upported by ONR. Contr:lct NOOOI-l-34-K. 0502:md NSF Gl':tnl DCR-8451393, wilh matching funds from AT&T. • o.:pt of Ma...

Convolution type Calderr on-Zygmund singular integral operators with rough kernels p.v. (x)=jxj n are studied. A condition on implying that the corresponding singular integrals and maximal singular integrals map L p ! L p for 1 < p < 1 is obtained. This condition is shown to be diierent from the condition 2 H 1 (S n?1).