background and aim: an important criterion for success assessment of implant-supported prostheses is marginal fit. vertical and horizontal discrepancy can result in loosening of the prosthetic screw, crestal bone resorption, peri-implantitis and loss of osseointegration. despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. the aim of this study was...

objective: this experimental in vitro study compared marginal adaptation of indirect composite, glass-ceramic inlays and direct composite. materials and methods: seventy-five recently extracted human molars were randomly divided into three groups (n=25) and mesio-occluso-distal cavities with the same dimensions were prepared in the teeth. indirect composite and glass-ceramic inlays were fabrica...

Up to isomorphism there are four symmetric (36,15,6) designs with automorphisms of order 7. Full automorphism group of one of them is the Chevalley group G(2, 2) ~ U(3,3) : Z2 of order 12096. Unitary group U(3,3) acts transitively on that design.

It has been shown that if a (v,k,λ )-symmetric design with λ ≤ 3 admits a flag-transitive automorphism group G which acts primitively on points, then G must be of affine or almost simple type. Here we extend the result to λ = 4.

We develop a theory of generalized presentations of groups. We give generalized presentations of the symmetric group Σ(X) and of the automorphism group of the free group of countable rank, Aut(Fω).

A k–factorization of Kv of type (r, s) consists of k–factors each of which is the disjoint union of r copies of Kk+1 and s copies of Kk,k. By means of what we call the patterned k–factorization Fk(D) over an arbitrary group D of order 2s + 1, it is shown that a k-factorization of type (1, s) exists for any k > 2 and for any s > 1 with D being an automorphism group acting sharply transitively on...

We describe symmetric designs D with classical parameters v=(q 6 − 1)/(q − 1), k=(q 5 − 1)/(q − 1), l=(q 4 − 1)/(q − 1), and automorphism group Aut(G 2 (q)).

The existence of triplewhist tournaments for v players has recently been solved for all values of v except v = 17. For v = 12 and v = 13 a complete enumeration has shown the nonexistence of TWh (v), while constructions of TWh (v) have been presented for v > 17. For several values of v existence has been shown by constructing a TWh (v) with a prescribed, usually cyclic, automorphism group. In th...

In this paper we find a necessary and sufficient condition for a finite nilpotent group to have an abelian central automorphism group.