3,215 research outputs found
First-order Nilpotent Minimum Logics: first steps
Following the lines of the analysis done in [BPZ07, BCF07] for first-order
G\"odel logics, we present an analogous investigation for Nilpotent Minimum
logic NM. We study decidability and reciprocal inclusion of various sets of
first-order tautologies of some subalgebras of the standard Nilpotent Minimum
algebra. We establish a connection between the validity in an NM-chain of
certain first-order formulas and its order type. Furthermore, we analyze
axiomatizability, undecidability and the monadic fragments.Comment: In this version of the paper the presentation has been improved. The
introduction section has been rewritten, and many modifications have been
done to improve the readability; moreover, numerous references have been
added. Concerning the technical side, some proofs has been shortened or made
more clear, but the mathematical content is substantially the same of the
previous versio
The variety generated by all the ordinal sums of perfect MV-chains
We present the logic BL_Chang, an axiomatic extension of BL (see P. H\'ajek -
Metamathematics of fuzzy logic - 1998, Kluwer) whose corresponding algebras
form the smallest variety containing all the ordinal sums of perfect MV-chains.
We will analyze this logic and the corresponding algebraic semantics in the
propositional and in the first-order case. As we will see, moreover, the
variety of BL_Chang-algebras will be strictly connected to the one generated by
Chang's MV-algebra (that is, the variety generated by all the perfect
MV-algebras): we will also give some new results concerning these last
structures and their logic.Comment: This is a revised version of the previous paper: the modifications
concern essentially the presentation. The scientific content is substantially
unchanged. The major variations are: Definition 2.7 has been improved.
Section 3.1 has been made more compact. A new reference, [Bus04], has been
added. There is some minor modification in Section 3.
A temporal semantics for Nilpotent Minimum logic
In [Ban97] a connection among rough sets (in particular, pre-rough algebras)
and three-valued {\L}ukasiewicz logic {\L}3 is pointed out. In this paper we
present a temporal like semantics for Nilpotent Minimum logic NM ([Fod95,
EG01]), in which the logic of every instant is given by {\L}3: a completeness
theorem will be shown. This is the prosecution of the work initiated in [AGM08]
and [ABM09], in which the authors construct a temporal semantics for the
many-valued logics of G\"odel ([G\"od32], [Dum59]) and Basic Logic ([H\'aj98]).Comment: 19 pages, 2 table
Liquidity, risk and occupational choices
We explore whether financial constraints matter and which financial constraints matter the most in the choice of becoming an entrepreneur. We exploit a randomly assigned welfare program in rural Mexico to show that cash transfers significantly increase entry into entrepreneurship, thereby providing evidence of financial constraints. We then develop a simple model to highlight how liquidity and insurance constraints respond differently to the time profile of expected cash transfers. Exploiting the cross-households variation in the timing of these transfers, we find that current occupational choices are significantly more responsive to the amount of transfers expected for the future than to the amount of transfers currently received. We interpret these findings as evidence that the program has been effective in promoting micro-entrepreneurship by enhancing the willingness to bear risk.financial constraints ; entrepreneurship ; insurance, liquidity
Liquidity, Risk, and Occupational Choices.
We explore which financial constraints matter the most in the choice of becoming an entrepreneur. We consider a randomly assigned welfare program in rural Mexico and show that cash transfers signi cantly increase entry into entrepreneurship. We then exploit the cross-household variation in the timing of these transfers and nd that current occupational choices are signi cantly more responsive to the transfers expected for the future than to those currently received. Guided by a simple occu- pational choice model, we argue that the program has promoted entrepreneurship by enhancing the willingness to bear risk as opposed to simply relaxing current liquidity constraints.insurance; entrepreneurship; Financial constraints; liquidity;
Radio Loud AGN in the 2XMMi catalogue
We are carrying out a search for all radio loud Active Galactic Nuclei
observed with XMM-Newton, including targeted and field sources to perform a
multi-wavelength study of these objects. We have cross-correlated the
Veron-Cetty & Veron (2010) catalogue with the XMM-Newton Serendipitous Source
Catalogue (2XMMi) and found about 4000 matched sources. A literature search
provided radio, optical, and X-ray data for 403 sources. Here we summarize the
first results of our study.Comment: Proceedings og the IAU275 Symposium: Jets at all scale
Synergy-based Hand Pose Sensing: Reconstruction Enhancement
Low-cost sensing gloves for reconstruction posture provide measurements which
are limited under several regards. They are generated through an imperfectly
known model, are subject to noise, and may be less than the number of Degrees
of Freedom (DoFs) of the hand. Under these conditions, direct reconstruction of
the hand posture is an ill-posed problem, and performance can be very poor.
This paper examines the problem of estimating the posture of a human hand
using(low-cost) sensing gloves, and how to improve their performance by
exploiting the knowledge on how humans most frequently use their hands. To
increase the accuracy of pose reconstruction without modifying the glove
hardware - hence basically at no extra cost - we propose to collect, organize,
and exploit information on the probabilistic distribution of human hand poses
in common tasks. We discuss how a database of such an a priori information can
be built, represented in a hierarchy of correlation patterns or postural
synergies, and fused with glove data in a consistent way, so as to provide a
good hand pose reconstruction in spite of insufficient and inaccurate sensing
data. Simulations and experiments on a low-cost glove are reported which
demonstrate the effectiveness of the proposed techniques.Comment: Submitted to International Journal of Robotics Research (2012
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