On the Possibility of Hallucinations

Many take the possibility of hallucinations to imply that a relationalist account, according to which perceptual experiences are constituted by direct relations to ordinary mind-independent objects, is false. The common reaction among relationalists is to adopt a disjunctivist view that denies that hallucinations have the same nature as perceptual experiences. This paper proposes a non-disjunctivist response to the argument from hallucination by arguing that the alleged empirical and a priori evidence in support of the possibility of hallucinations is inconclusive. A corollary upshot of the article is that whether hallucinations are possible or not is still an open empirical question

Relative Upper Confidence Bound for the K-Armed Dueling Bandit Problem

This paper proposes a new method for the K-armed dueling bandit problem, a variation on the regular K-armed bandit problem that offers only relative feedback about pairs of arms. Our approach extends the Upper Confidence Bound algorithm to the relative setting by using estimates of the pairwise probabilities to select a promising arm and applying Upper Confidence Bound with the winner as a benchmark. We prove a finite-time regret bound of order O(log t). In addition, our empirical results using real data from an information retrieval application show that it greatly outperforms the state of the art.Comment: 13 pages, 6 figure

Copeland Dueling Bandits

A version of the dueling bandit problem is addressed in which a Condorcet winner may not exist. Two algorithms are proposed that instead seek to minimize regret with respect to the Copeland winner, which, unlike the Condorcet winner, is guaranteed to exist. The first, Copeland Confidence Bound (CCB), is designed for small numbers of arms, while the second, Scalable Copeland Bandits (SCB), works better for large-scale problems. We provide theoretical results bounding the regret accumulated by CCB and SCB, both substantially improving existing results. Such existing results either offer bounds of the form $O(K \log T)$ but require restrictive assumptions, or offer bounds of the form $O(K^2 \log T)$ without requiring such assumptions. Our results offer the best of both worlds: $O(K \log T)$ bounds without restrictive assumptions.Comment: 33 pages, 8 figure

Evaluating Endometrial Thickness and Vascular Ultrasound Pattern and Pregnancy Outcomes in Intrauterine Insemination Cycle

The current study aims to investigate whether endometrial thickness and pattern, and blood flow in color Doppler of sonography on the day of administration is a predictor of intrauterine insemination (IUI) success. The study was designed as a cross-sectional prospective clinical study with one-hundred women undergoing an IUI cycle. Interventions of the study include endometrial thickness and pattern and color Doppler flow on the day of administration and cycle parameters were compared between pregnant and non-pregnant patients. Main outcome measures are endometrial thickness and patterns and blood flow in color Doppler. The results showed that the overall pregnancy rate was 38%, which mean that endometrial blood flow on the day of administration was significantly greater in cycles, pregnancy achieved, but endometrial thickness and pattern of sonography were found to have no predictive value on endometrial receptivity. In multi-variant analysis, the following variable affected the pregnancy rate: the women’s age, duration of infertility, type, number of IUI cycle, the number of ampules to stimulate dominant follicle, sperm count. In our study, this variability was found to have no predictive value on the outcome of IUI but endometrial flow in color Doppler was positively associated pregnancy outcome