12,314 research outputs found
The Structure of a Graph Inverse Semigroup
Given any directed graph E one can construct a graph inverse semigroup G(E),
where, roughly speaking, elements correspond to paths in the graph. In this
paper we study the semigroup-theoretic structure of G(E). Specifically, we
describe the non-Rees congruences on G(E), show that the quotient of G(E) by
any Rees congruence is another graph inverse semigroup, and classify the G(E)
that have only Rees congruences. We also find the minimum possible degree of a
faithful representation by partial transformations of any countable G(E), and
we show that a homomorphism of directed graphs can be extended to a
homomorphism (that preserves zero) of the corresponding graph inverse
semigroups if and only if it is injective.Comment: 19 pages; corrected errors, improved organization, strengthened a
result (Theorem 20), added reference
Modeling the large-scale redshift-space 3-point correlation function of galaxies
We present a configuration-space model of the large-scale galaxy 3-point
correlation function (3PCF) based on leading-order perturbation theory and
including redshift space distortions (RSD). This model should be useful in
extracting distance-scale information from the 3PCF via the Baryon Acoustic
Oscillation (BAO) method. We include the first redshift-space treatment of
biasing by the baryon-dark matter relative velocity. Overall, on large scales
the effect of RSD is primarily a renormalization of the 3PCF that is roughly
independent of both physical scale and triangle opening angle; for our adopted
and bias values, the rescaling is a factor of . We
also present an efficient scheme for computing 3PCF predictions from our model,
important for allowing fast exploration of the space of cosmological parameters
in future analyses.Comment: 23 pages, 11 figures, submitted MNRA
Traceability Adoption by Specialty Crop Producers in California
Surveys were sent to specialty crop producers in California, predominantly grower-packer-shippers, during the first half of 2006 to better understand the motives for traceability adoption. The questions in our survey allowed respondents to consider the benefits of tracing. A representative tracing system for melons was developed and costs for the system were collected from industry sources. Values were assigned to the benefits of traceability based on the cost of the representative system, responses collected in our survey, and using Borda’s rule. Results suggest that litigation concerns and firm reputation are the key drivers for maintaining traceability.Borda’s rule, California, partial budget, specialty crops, survey, traceability, Agribusiness, Crop Production/Industries,
- …