4,693 research outputs found
Algorithms in algebraic number theory
In this paper we discuss the basic problems of algorithmic algebraic number
theory. The emphasis is on aspects that are of interest from a purely
mathematical point of view, and practical issues are largely disregarded. We
describe what has been done and, more importantly, what remains to be done in
the area. We hope to show that the study of algorithms not only increases our
understanding of algebraic number fields but also stimulates our curiosity
about them. The discussion is concentrated of three topics: the determination
of Galois groups, the determination of the ring of integers of an algebraic
number field, and the computation of the group of units and the class group of
that ring of integers.Comment: 34 page
Landauer's principle as a special case of Galois connection
It is demonstrated how to construct a Galois connection between two related
systems with entropy. The construction, called the Landauer's connection,
describes coupling between two systems with entropy. It is straightforward and
transfers changes in one system to the other one preserving ordering structure
induced by entropy. The Landauer's connection simplifies the description of the
classical Landauer's principle for computational systems. Categorification and
generalization of the Landauer's principle opens area of modelling of various
systems in presence of entropy in abstract terms.Comment: 24 pages, 3 figure
Revisiting LFSMs
Linear Finite State Machines (LFSMs) are particular primitives widely used in
information theory, coding theory and cryptography. Among those linear
automata, a particular case of study is Linear Feedback Shift Registers (LFSRs)
used in many cryptographic applications such as design of stream ciphers or
pseudo-random generation. LFSRs could be seen as particular LFSMs without
inputs.
In this paper, we first recall the description of LFSMs using traditional
matrices representation. Then, we introduce a new matrices representation with
polynomial fractional coefficients. This new representation leads to sparse
representations and implementations. As direct applications, we focus our work
on the Windmill LFSRs case, used for example in the E0 stream cipher and on
other general applications that use this new representation.
In a second part, a new design criterion called diffusion delay for LFSRs is
introduced and well compared with existing related notions. This criterion
represents the diffusion capacity of an LFSR. Thus, using the matrices
representation, we present a new algorithm to randomly pick LFSRs with good
properties (including the new one) and sparse descriptions dedicated to
hardware and software designs. We present some examples of LFSRs generated
using our algorithm to show the relevance of our approach.Comment: Submitted to IEEE-I
A special point problem of Andr\'e-Pink-Zannier in the universal family of abelian varieties
The Andr\'e-Pink-Zannier conjecture concerns the intersection of subvarieties
and the generalized Hecke orbit of a given point in mixed Shimura varieties. It
is part of the Zilber-Pink conjecture. In this paper we focus on the universal
family of principally polarized abelian varieties. We explain the moduli
interpretation of the conjecture in this case and prove several different cases
for this conjecture: its overlap with the Andr\'e-Oort conjecture; when the
subvariety is contained in an abelian scheme over a curve and the point is a
torsion point on its fiber; when the subvariety is a curve.Comment: Removed the algebraic point assumption. Comments are welcome
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