Search results for "Coherence"
showing 10 items of 905 documents
Probabilistic entailment and iterated conditionals
2020
In this paper we exploit the notions of conjoined and iterated conditionals, which are defined in the setting of coherence by means of suitable conditional random quantities with values in the interval $[0,1]$. We examine the iterated conditional $(B|K)|(A|H)$, by showing that $A|H$ p-entails $B|K$ if and only if $(B|K)|(A|H) = 1$. Then, we show that a p-consistent family $\mathcal{F}=\{E_1|H_1,E_2|H_2\}$ p-entails a conditional event $E_3|H_3$ if and only if $E_3|H_3=1$, or $(E_3|H_3)|QC(\mathcal{S})=1$ for some nonempty subset $\mathcal{S}$ of $\mathcal{F}$, where $QC(\mathcal{S})$ is the quasi conjunction of the conditional events in $\mathcal{S}$. Then, we examine the inference rules $A…
Conditional Random Quantities and Compounds of Conditionals
2013
In this paper we consider finite conditional random quantities and conditional previsions assessments in the setting of coherence. We use a suitable representation for conditional random quantities; in particular the indicator of a conditional event $E|H$ is looked at as a three-valued quantity with values 1, or 0, or $p$, where $p$ is the probability of $E|H$. We introduce a notion of iterated conditional random quantity of the form $(X|H)|K$ defined as a suitable conditional random quantity, which coincides with $X|HK$ when $H \subseteq K$. Based on a recent paper by S. Kaufmann, we introduce a notion of conjunction of two conditional events and then we analyze it in the setting of cohere…
Compound conditionals, Fr\'echet-Hoeffding bounds, and Frank t-norms
2021
Abstract In this paper we consider compound conditionals, Frechet-Hoeffding bounds and the probabilistic interpretation of Frank t-norms. By studying the solvability of suitable linear systems, we show under logical independence the sharpness of the Frechet-Hoeffding bounds for the prevision of conjunctions and disjunctions of n conditional events. In addition, we illustrate some details in the case of three conditional events. We study the set of all coherent prevision assessments on a family containing n conditional events and their conjunction, by verifying that it is convex. We discuss the case where the prevision of conjunctions is assessed by Lukasiewicz t-norms and we give explicit s…
Generalized probabilistic modus ponens
2017
Modus ponens (from A and “if A then C” infer C) is one of the most basic inference rules. The probabilistic modus ponens allows for managing uncertainty by transmitting assigned uncertainties from the premises to the conclusion (i.e., from P(A) and P(C|A) infer P(C)). In this paper, we generalize the probabilistic modus ponens by replacing A by the conditional event A|H. The resulting inference rule involves iterated conditionals (formalized by conditional random quantities) and propagates previsions from the premises to the conclusion. Interestingly, the propagation rules for the lower and the upper bounds on the conclusion of the generalized probabilistic modus ponens coincide with the re…
Conditional Random Quantities and Iterated Conditioning in the Setting of Coherence
2013
We consider conditional random quantities (c.r.q.’s) in the setting of coherence. Given a numerical r.q. X and a non impossible event H, based on betting scheme we represent the c.r.q. X|H as the unconditional r.q. XH + μH c , where μ is the prevision assessed for X|H. We develop some elements for an algebra of c.r.q.’s, by giving a condition under which two c.r.q.’s X|H and Y|K coincide. We show that X|HK coincides with a suitable c.r.q. Y|K and we apply this representation to Bayesian updating of probabilities, by also deepening some aspects of Bayes’ formula. Then, we introduce a notion of iterated c.r.q. (X|H)|K, by analyzing its relationship with X|HK. Our notion of iterated conditiona…
Transitive Reasoning with Imprecise Probabilities
2015
We study probabilistically informative (weak) versions of transitivity by using suitable definitions of defaults and negated defaults in the setting of coherence and imprecise probabilities. We represent \(\text{ p-consistent }\) sequences of defaults and/or negated defaults by g-coherent imprecise probability assessments on the respective sequences of conditional events. Finally, we present the coherent probability propagation rules for Weak Transitivity and the validity of selected inference patterns by proving p-entailment of the associated knowledge bases.
Intraoperative dexamethasone intravitreal implant in diabetic macular edema patients undergoing phacoemulsification: The CataDex study
2021
Purpose To assess the impact of preoperative intravitreal dexamethasone implant (DexI) on functional and anatomic outcomes in patients with diabetic macular edema (DME) who underwent phacoemulsification cataract surgery. Methods Prospective and non-comparative study conducted on consecutive DME patients undergoing cataract surgery. DexI was administered 15 days before surgery and in a pro re nata regime after surgery. Main outcome measures were mean change in central retinal thickness (CRT), central subfield thickness (CST), total macular volume (TMV), and central subfield volume (CSV) from baseline to month-12. Secondary outcome was mean change in best corrected visual acuity (BCVA). Resul…
Dynamical decoupling efficiency versus quantum non-Markovianity
2015
We investigate the relationship between non-Markovianity and the effectiveness of a dynamical decoupling protocol for qubits undergoing pure dephasing. We consider an exact model in which dephasing arises due to a bosonic environment with a spectral density of the Ohmic class. This is parametrised by an Ohmicity parameter by changing which we can model both Markovian and non-Markovian environments. Interestingly, we find that engineering a non-Markovian environment is detrimental to the efficiency of the dynamical decoupling scheme, leading to a worse coherence preservation. We show that each dynamical decoupling pulse reverses the flow of quantum information and, on this basis, we investig…
Public Purchasing and Eco-labelling Schemes: Making the Connection and Reinforcing Policy Coherence
2004
Many governments have promoted eco-labelling schemes as an accurate information-based policy to regulate environmental problems. This paper argues that governments should integrate eco-labelling into their purchasing decisions, both to benefit the environment directly and to reinforce ecolabelling programs as a means to influence private purchasers. Both effects could be quite significant given that governments are large purchasers of goods and services. After reviewing the main barriers and potentialities for greening procurement markets, we explore several ways by which green public procurement can promote the overall diffusion of eco-labelled products. JEL codes: H57; Q 28
A wavelet analysis of the ripple effect in UK regional housing markets
2021
Abstract The paper aims at gaining insights on the spatio-temporal mechanism of house price spillovers, also known as ripple effect, among 12 UK regional housing markets, over the period 1973–2018. From a policy perspective, it is essential to discriminate if the effects of a shock decay more slowly along the geographical dimension as compared to the decay along the time dimension. We enter the debate in a novel manner by using some wavelet analysis tools (wavelet coherence and phase differences amongst others) which reveal the spectral characteristics of a series and show how different periodic components of housing returns evolve over time. Results are interesting. Spillovers from London …