A Cut-Free Sequent Calculus for Defeasible Erotetic Inferences

In recent years, the effort to formalize erotetic inferences (i.e., inferences to and from questions) has become a central concern for those working in erotetic logic. However, few have sought to formulate a proof theory for these inferences. To fill this lacuna, we construct a calculus for (classes of) sequents that are sound and complete for two species of erotetic inferences studied by Inferential Erotetic Logic (IEL): erotetic evocation and regular erotetic implication. While an attempt has been made to axiomatize the former in a sequent system, there is currently no proof theory for the latter. Moreover, the extant axiomatization of erotetic evocation fails to capture its defeasible character and provides no rules for introducing or eliminating question-forming operators. In contrast, our calculus encodes defeasibility conditions on sequents and provides rules governing the introduction and elimination of erotetic formulas. We demonstrate that an elimination theorem holds for a version of the cut rule that applies to both declarative and erotetic formulas and that the rules for the axiomatic account of question evocation in IEL are admissible in our system

On representation varieties of Artin groups, projective arrangements and the fundamental groups of smooth complex algebraic varieties

We prove that for any affine variety S defined over Q there exist Shephard and Artin groups G such that a Zariski open subset U of S is biregular isomorphic to a Zariski open subset of the character variety Hom(G, PO(3))//PO(3). The subset U contains all real points of S . As an application we construct new examples of finitely-presented groups which are not fundamental groups of smooth complex algebraic varieties.Comment: 68 pages 15 figure

Universality theorems for configuration spaces of planar linkages

We prove realizability theorems for vector-valued polynomial mappings, real-algebraic sets and compact smooth manifolds by moduli spaces of planar linkages. We also establish a relation between universality theorems for moduli spaces of mechanical linkages and projective arrangements.Comment: 45 pages, 15 figures. See also http://www.math.utah.edu/~kapovich/eprints.htm

Perspectives, Questions, and Epistemic Value

Many epistemologists endorse true-belief monism, the thesis that only true beliefs are of fundamental epistemic value. However, this view faces formidable counterexamples. In response to these challenges, we alter the letter, but not the spirit, of true-belief monism. We dub the resulting view “inquisitive truth monism”, which holds that only true answers to relevant questions are of fundamental epistemic value. Which questions are relevant is a function of an inquirer’s perspective, which is characterized by his/her interests, social role, and background assumptions. Using examples of several different scientific practices, we argue that inquisitive truth monism outperforms true-belief monism

On representation varieties of 3-manifold groups

We prove universality theorems ("Murphy's Laws") for representation schemes of fundamental groups of closed 3-dimensional manifolds. We show that germs of SL(2,C)-representation schemes of such groups are essentially the same as germs of schemes of over rational numbers.Comment: 28 page

Factors influencing delays in patient access to new medicines in Canada: a retrospective study of reimbursement processes in public drug plans

© 2019 Salek, Lussier Hoskyn, Johns, Allen and Sehgal.Individuals who rely on public health payers to access new medicines can access fewer innovative medicines and must wait longer in Canada compared to major markets around the world. New medicines/indications approved by Health Canada and reviewed for eligibility for reimbursement by the Common Drug Review or the pan-Canadian Oncology Drug Review (CDR/pCODR) from the beginning of 2012 through to the end of December 2016 were analyzed, with data taken from the relevant bodies’ websites and collected by IQVIA. This analysis investigated individual review segments – Notice of Compliance (NOC) to Health Technology Assessment (HTA) submission, HTA review time, pan-Canadian Pharmaceutical Alliance (pCPA) negotiation time, and public reimbursement decision time, and analyzed the trends of each over time and contributions to overall time to listing decisions. Average overall timelines for public reimbursement after NOC were long and most of this time is taken up by HTA and pCPA processes, at 236 and 273 days, respectively. This study confirms that Canadian public reimbursement delays from 2013-2014 to 2015-2016 lengthened from NOC to listing (Quebec + 53%, first provincial listing + 38%, and country-wide listing + 22%), reaching 499, 505, and 571 days, respectively. Over the same period, time from NOC to completion of HTA has increased by 33%, and time from post-HTA to first provincial listing by 44%. The pCPA process appears to be the main contributor to this increasing time trend, and although some provinces could be listing more quickly post-pCPA, they appear to be listing fewer products. Reasons for large delays in time to listing include the many-layered sequential process of reviews conducted before public drug plans decide whether to provide access to new innovative medicines. Although there has been some headway made in certain parts of the review processes (e.g., pre-NOC HTA), total time to listing continues to increase, seemingly due to the pCPA process and other additional review processes by drug plans. More clarity in the pCPA and provincial decision-making processes and better coordination between HTA, pCPA, and provincial decision-making processes is needed to increase predictability in the processes and reduce timelines for Canadian patients and manufacturers.Peer reviewedFinal Published versio

Inference, Explanation, and Asymmetry

Explanation is asymmetric: if A explains B, then B does not explain A. Tradition- ally, the asymmetry of explanation was thought to favor causal accounts of explanation over their rivals, such as those that take explanations to be inferences. In this paper, we develop a new inferential approach to explanation that outperforms causal approaches in accounting for the asymmetry of explanation