Proving Type Class Laws for Haskell

Type classes in Haskell are used to implement ad-hoc polymorphism, i.e. a way to ensure both to the programmer and the compiler that a set of functions are defined for a specific data type. All instances of such type classes are expected to behave in a certain way and satisfy laws associated with the respective class. These are however typically just stated in comments and as such, there is no real way to enforce that they hold. In this paper we describe a system which allows the user to write down type class laws which are then automatically instantiated and sent to an inductive theorem prover when declaring a new instance of a type class.Comment: Presented at the Symposium for Trends in Functional Programming, 201

Emergence of qualia from brain activity or from an interaction of proto-consciousness with the brain: which one is the weirder? Available evidence and a research agenda

This contribution to the science of consciousness aims at comparing how two different theories can explain the emergence of different qualia experiences, meta-awareness, meta-cognition, the placebo effect, out-of-body experiences, cognitive therapy and meditation-induced brain changes, etc. The first theory postulates that qualia experiences derive from specific neural patterns, the second one, that qualia experiences derive from the interaction of a proto-consciousness with the brain\u2019s neural activity. From this comparison it will be possible to judge which one seems to better explain the different qualia experiences and to offer a more promising research agenda

Adult chest radiograph reporting by radiographers: Preliminary data from an in-house audit programme

Aim To examine the adult chest radiograph (CXR) reporting performance of a reporting radiographer in clinical practice using different audit systems; single radiologist and two radiologists, with clinical review of discordant cases. Materials and methods 100 chest radiographs (CXRs) were drawn randomly from a consecutive series of 4800 CXRs which had been reported during a nine month period at a district general hospital by a radiographer after two years of training. Diagnostic outcomes were normal or abnormal, and agreement with the reporting radiographer or not. There was 50% duplication of CXRs reported between three radiologists. Concordance rates were determined for the radiographer-radiologist and inter-radiologist interpretations. Independent clinical review of discordant cases was performed to establish the final diagnosis. Results Ninety-nine cases were reviewed, with 40 cases deemed abnormal by at least one radiologist. Consensus was found with the radiographers report in 59 normal and 33 abnormal CXRs reviewed by two radiologists (96.7% and 86.8% respectively). Seven CXR reports were discrepant with clinical review: mediastinal lymphadenopathy was missed by both radiologist and radiographer; linear atelectasis was reported by two radiologists but not the radiographer. Three cases were over-interpreted and on two occasions at least one radiologist agreed with the radiographer. There was very high concordance between the radiographer and each radiologist, 96%, 96% and 92% respectively. Conclusions This study suggested that regular audit, which incorporates case note review and discrepant reporting within a multidisciplinary setting, should contribute to safe practice

Removing Algebraic Data Types from Constrained Horn Clauses Using Difference Predicates

We address the problem of proving the satisfiability of Constrained Horn Clauses (CHCs) with Algebraic Data Types (ADTs), such as lists and trees. We propose a new technique for transforming CHCs with ADTs into CHCs where predicates are defined over basic types, such as integers and booleans, only. Thus, our technique avoids the explicit use of inductive proof rules during satisfiability proofs. The main extension over previous techniques for ADT removal is a new transformation rule, called differential replacement, which allows us to introduce auxiliary predicates corresponding to the lemmas that are often needed when making inductive proofs. We present an algorithm that uses the new rule, together with the traditional folding/unfolding transformation rules, for the automatic removal of ADTs. We prove that if the set of the transformed clauses is satisfiable, then so is the set of the original clauses. By an experimental evaluation, we show that the use of the differential replacement rule significantly improves the effectiveness of ADT removal, and we show that our transformation-based approach is competitive with respect to a well-established technique that extends the CVC4 solver with induction.Comment: 10th International Joint Conference on Automated Reasoning (IJCAR 2020) - version with appendix; added DOI of the final authenticated Springer publication; minor correction

Recurrent respiratory papillomatosis: an overview of current thinking and treatment

Human papillomaviruses (HPV) infection in benign laryngeal papillomas is well established. The vast majority of recurrent respiratory papillomatosis lesions are due to HPV types 6 and 11. Human papillomaviruses are small non-enveloped viruses (>8 kb), that replicate within the nuclei of infected host cells. Infected host basal cell keratinocytes and papillomas arise from the disordered proliferation of these differentiating keratinocytes. Surgical debulking of papillomas is currently the treatment of choice; newer surgical approaches utilizing microdebriders are replacing laser ablation. Surgery aims to secure an adequate airway and improve and maintain an acceptable quality of voice. Adjuvant treatments currently used include cidofovir, indole-3-carbinol, ribavirin, mumps vaccine, and photodynamic therapy. The recent licensing of prophylactic HPV vaccines is a most interesting development. The low incidence of RRP does pose significant problems in recruitment of sufficient numbers to show statistical significance. Large multi-centre collaborative clinical trials are therefore required. Even so, sufficient clinical follow-up data would take several years