1,611 research outputs found
Corecursive Algebras, Corecursive Monads and Bloom Monads
An algebra is called corecursive if from every coalgebra a unique
coalgebra-to-algebra homomorphism exists into it. We prove that free
corecursive algebras are obtained as coproducts of the terminal coalgebra
(considered as an algebra) and free algebras. The monad of free corecursive
algebras is proved to be the free corecursive monad, where the concept of
corecursive monad is a generalization of Elgot's iterative monads, analogous to
corecursive algebras generalizing completely iterative algebras. We also
characterize the Eilenberg-Moore algebras for the free corecursive monad and
call them Bloom algebras
Enriched weakness
The basic notions of category theory, such as limit, adjunction, and
orthogonality, all involve assertions of the existence and uniqueness of
certain arrows. Weak notions arise when one drops the uniqueness requirement
and asks only for existence. The enriched versions of the usual notions involve
certain morphisms between hom-objects being invertible; here we introduce
enriched versions of the weak notions by asking that the morphisms between
hom-objects belong to a chosen class of "surjections". We study in particular
injectivity (weak orthogonality) in the enriched context, and illustrate how it
can be used to describe homotopy coherent structures.Comment: 25 pages; v2 minor changes, to appear in JPA
Limits of small functors
For a small category K enriched over a suitable monoidal category V, the free
completion of K under colimits is the presheaf category [K*,V]. If K is large,
its free completion under colimits is the V-category PK of small presheaves on
K, where a presheaf is small if it is a left Kan extension of some presheaf
with small domain. We study the existence of limits and of monoidal closed
structures on PK.Comment: 17 page
Improved Acceleration of the GPU Fourier Domain Acceleration Search Algorithm
We present an improvement of our implementation of the Correlation Technique
for the Fourier Domain Acceleration Search (FDAS) algorithm on Graphics
Processor Units (GPUs) (Dimoudi & Armour 2015; Dimoudi et al. 2017). Our new
improved convolution code which uses our custom GPU FFT code is between 2.5 and
3.9 times faster the than our cuFFT-based implementation (on an NVIDIA P100)
and allows for a wider range of filter sizes then our previous version. By
using this new version of our convolution code in FDAS we have achieved 44%
performance increase over our previous best implementation. It is also
approximately 8 times faster than the existing PRESTO GPU implementation of
FDAS (Luo 2013). This work is part of the AstroAccelerate project (Armour et
al. 2002), a many-core accelerated time-domain signal processing library for
radio astronomy.Comment: proceeding from ADASS XXVII conference, 4 page
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