Combinatorial Classification of Chemical Mechanisms

1984 ◽  
Vol 44 (4) ◽  
pp. 784-792 ◽  
Author(s):  
Peter H. Sellers
Keyword(s):  
Chemical Mechanisms ◽  
Combinatorial Classification

scholarly journals Multiplicity-Free Schubert Calculus

2010 ◽  
Vol 53 (1) ◽  
pp. 171-186 ◽  
Author(s):  
Hugh Thomas ◽  
Alexander Yong
Keyword(s):  
Algebraic Geometry ◽  
Schubert Calculus ◽  
Chow Ring ◽  
Free Products ◽  
Linear Basis ◽  
Combinatorial Classification ◽  
Schubert Classes ◽  
Multiplicity Free

AbstractMultiplicity-free algebraic geometry is the study of subvarieties Y ⊆ X with the “smallest invariants” as witnessed by a multiplicity-free Chow ring decomposition of [Y] ∈ A*(X) into a predetermined linear basis.This paper concerns the case of Richardson subvarieties of the Grassmannian in terms of the Schubert basis. We give a nonrecursive combinatorial classification of multiplicity-free Richardson varieties, i.e., we classify multiplicity-free products of Schubert classes. This answers a question of W. Fulton.

scholarly journals Combinatorial classification of quantum lens spaces

2018 ◽  
Vol 297 (2) ◽  
pp. 339-365
Author(s):  
Peter Jensen ◽  
Frederik Klausen ◽  
Peter Rasmussen
Keyword(s):  
Lens Spaces ◽  
Combinatorial Classification

Quadratic-monomial generated domains from mixed signed, directed graphs

2019 ◽  
Vol 29 (02) ◽  
pp. 279-308
Author(s):  
Michael A. Burr ◽  
Drew J. Lipman
Keyword(s):  
Directed Graphs ◽  
Complete Characterization ◽  
Combinatorial Structure ◽  
Signed Directed Graph ◽  
Odd Cycle ◽  
Combinatorial Classification ◽  
Special Case ◽  
Text Condition

Determining whether an arbitrary subring [Formula: see text] of [Formula: see text] is a normal or Cohen-Macaulay domain is, in general, a nontrivial problem, even in the special case of a monomial generated domain. We provide a complete characterization of the normality, normalizations, and Serre’s [Formula: see text] condition for quadratic-monomial generated domains. For a quadratic-monomial generated domain [Formula: see text], we develop a combinatorial structure that assigns, to each quadratic monomial of the ring, an edge in a mixed signed, directed graph [Formula: see text], i.e. a graph with signed edges and directed edges. We classify the normality and the normalizations of such rings in terms of a generalization of the combinatorial odd cycle condition on [Formula: see text]. We also generalize and simplify a combinatorial classification of Serre’s [Formula: see text] condition for such rings and construct non-Cohen–Macaulay rings.

scholarly journals Combinatorial classification of piecewise hereditary algebras

2011 ◽  
Vol 23 (6) ◽  
Author(s):  
Marcelo Lanzilotta ◽  
Maria Julia Redondo ◽  
Rachel Taillefer
Keyword(s):  
Combinatorial Classification ◽  
Hereditary Algebras

scholarly journals A covalent protein–DNA 5′-product adduct is generated following AP lyase activity of human ALKBH1 (AlkB homologue 1)

2013 ◽  
Vol 452 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Tina A. Müller ◽  
Megan M. Andrzejak ◽  
Robert P. Hausinger
Keyword(s):  
Dna Adduct ◽  
Covalent Attachment ◽  
Main Site ◽  
Chemical Mechanisms ◽  
Covalent Adduct ◽  
Lysine Residues ◽  
Lyase Activity ◽  
Ap Lyase ◽  
Covalent Intermediate

ALKBH1 (AlkB homologue 1) is a mammalian AlkB (2-oxoglutarate-dependent dioxygenase) homologue that possesses AP (abasic or apurinic/apyrimidinic) lyase activity. The AP lyase reaction is catalysed by imine formation with an active site lysine residue, and a covalent intermediate can be trapped in the presence of NaBH4. Surprisingly, ALKBH1 also forms a stable protein–DNA adduct in the absence of a reducing agent. Experiments with different substrates demonstrated that the protein covalently binds to the 5′ DNA product, i.e. the fragment containing an α,β-unsaturated aldehyde. The N-terminal domain of ALKBH1 was identified as the main site of linkage with DNA. By contrast, mutagenesis studies suggest that the primary catalytic residue forming the imine linkage is Lys133, with Lys154 and other lysine residues in this region serving in opportunistic roles. These findings confirm the classification of ALKBH1 as an AP lyase, identify the primary and a secondary lysine residues involved in the lyase reaction, and demonstrate that the protein forms a covalent adduct with the 5′ DNA product. We propose two plausible chemical mechanisms to account for the covalent attachment.

A combinatorial classification of finite quasigroups

2017 ◽  
Vol 57 (6) ◽  
pp. 711-732
Author(s):  
I. P. Mishutushkin
Keyword(s):  
Combinatorial Classification
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