A constraint satisfaction problem is a permutation problem if it has the same number of values as variables, all variables have the same domain and any solution assigns a permutation of the values to the variables. The dual CSP interchanges the variables and values; the eeects of combining both sets of variables in a single CSP are discussed.

It is shown that in the variety of orthomodular lattices every hypersubstitution respecting all absorption laws either leaves the lattice operations unchanged or interchanges join and meet. Further, in a variety of lattices with an involutory antiautomorphism a semigroup generated by three involutory hypersubstitutions is described.

It is shown that the T-duality in σ-model with Kaluza-Klein metric, without or with a torsion term, can be interpreted as electric-magnetic duality for some of their solitonic solutions. Actually Buscher’s duality transformation interchanges the topological and Noether charges. ∗E-mail: tabriz [email protected]

Results of density functional theory calculations on possible mechanisms for formation of the diterpenoid cyclooctatin are described. These results are consistent with the involvement of an unexpected 1,3-alkyl shift that interconverts two cyclopropylcarbinyl carbocations and interchanges the positions of two carbon atoms in an 8-membered ring. Predictions for future experiments to provide furt...

We address the problem of finding the minimal number of block interchanges (exchange of two intervals) required to transform a duplicated linear genome into a tandem duplicated linear genome. We provide a formula for the distance as well as a polynomial time algorithm for the sorting problem.

The problem of explicit generation of unitary operators for atomic systems with degenerate energy levels is considered. The Lie algebra structure is used to derive constructive control schemes for the creation of arbitrary superposition states and selective population interchanges for a transition between two three-fold degenerate energy levels.

Here we study the pattern of amino acid interchanges at spatially, locally conserved regions in globally dissimilar and unrelated proteins. By using a method which completely separates the amino acid sequence from its respective structure, this work addresses the question of which properties of the amino acids are the most crucial for the stability of conserved structural motifs. The proteins a...

A magnetized, centrifugally confined plasma is subjected to a 3D MHD stability test. Ordinarily, the system is expected to be grossly unstable to "flute" interchanges of field lines. Numerical simulation shows though that the system is stable on account of velocity shear. This allows consideration of a magnetically confined plasma for thermonuclear fusion that has a particularly simple coil con...