Trigg, P., J.R. Hindley and M.W. Bunder, Combinatory abstraction using B, B’ and friends, Theoretical Computer Science 135 (1994) 4055422. In this paper we characterise precisely the sets of terms whose abstractions can be defined using the following partial bases of combinators: { B, B’, I}, ( B, B’, I, W}, {B, B’, I, K}, { B, T, I}. [ B,T, I, W) and (B, T, I, K}. The reduction axioms for B’ a...

23 the advection problem. Experiments with the incompressible Navier Stokes equations for ows with closed streamlines need to be performed, employing distributive Gauss-Seidel relaxation, as shown in 4]. These will no doubt raise further questions. It is anticipated that the techniques investigated here will carry over to three dimensions, although the implementation will be considerably more c...

In the title mol-ecule, C(13)H(13)NO, the dihedral angle between the benzene and pyrrole rings is 1.05 (5)°. The cyclo-heptene ring adopts a slightly distorted boat conformation. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds form centrosymmetric dimers. A C-H⋯π inter-action, involving the benzene ring, is also found in the structure.

The flavor of a combinatorial optimization problem is to maximize an objective function over a set of valid points. In the case of TSP, the valid set of points S ⊆ {0, 1}( n 2) is the set of valid tours on the graph and the objective function is the minimum weight tour. In the cases that we will be interested in, the objective function will be linear. To make the problem amenable to linear prog...

Magnetic reconnection can be interpreted as a process in which the electromagnetic eld is frozen into a four-velocity eld in Minkowski space. For reconnec-tion to occur the four-velocity eld has to be a special type of stagnation ow. Prescribing this type of ow in a nite spatial domain allows the modelling of localized reconnection events and the investigation of examples of reconnection in reg...

In the title compound, C22H14S, the r.m.s. deviation from the mean plane of the four-fused-ring naphtho-thio-phene unit is 0.056 Å. The dihedral angle between the naphtho-thio-phene plane and the pendant phenyl ring is 67.24 (6)°. In the crystal, weak C-H⋯π and π-π stacking [minimum centroid-centroid separation = 3.7466 (10) Å] inter-actions are observed, which together lead to (010) sheets.

[reaction: see text] The enantioselective synthesis of the carbon skeleton of 6-deoxyerythronolide B has been achieved in 23 linear steps from propionaldehyde. The synthesis relies on an iterative approach employing an asymmetric acyl-thiazolidinethione propionate aldol reaction to establish eight of nine stereogenic centers. The remaining stereogenic center at C6 was set through a Myers alkyla...

The title compound, C(7)H(6)OS, crystallizes with two similar mol-ecules, 1 and 2, in the asymmetric unit. Both mol-ecules are essentially planar with r.m.s. deviations of 0.0193 and 0.0107 Å for the planes through the nine non-H atoms of mol-ecules 1 and 2, respectively. The thio-phene and 4,5-dihydro-cyclo-penta-dienone rings are inclined at 2.40 (13)° in 1 and 0.64 (13)° in 2. In the crystal...

Translocations involving the BCL-6 gene are common in the diffuse large cell subtype of non-Hodgkin's lymphoma. Invariably, the BCL-6 coding region is intact, but its 5' untranslated region is replaced with sequences from the translocation partner. The present study shows that BCL-6 expression is regulated in lymphocytes during mitogenic stimulation. Resting B and T lymphocytes contain high lev...