Machine-Checked Proofs For Realizability Checking Algorithms

Virtual integration techniques focus on building architectural models of systems that can be analyzed early in the design cycle to try to lower cost, reduce risk, and improve quality of complex embedded systems. Given appropriate architectural descriptions, assume/guarantee contracts, and compositional reasoning rules, these techniques can be used to prove important safety properties about the architecture prior to system construction. For these proofs to be meaningful, each leaf-level component contract must be realizable; i.e., it is possible to construct a component such that for any input allowed by the contract assumptions, there is some output value that the component can produce that satisfies the contract guarantees. We have recently proposed (in [1]) a contract-based realizability checking algorithm for assume/guarantee contracts over infinite theories supported by SMT solvers such as linear integer/real arithmetic and uninterpreted functions. In that work, we used an SMT solver and an algorithm similar to k-induction to establish the realizability of a contract, and justified our approach via a hand proof. Given the central importance of realizability to our virtual integration approach, we wanted additional confidence that our approach was sound. This paper describes a complete formalization of the approach in the Coq proof and specification language. During formalization, we found several small mistakes and missing assumptions in our reasoning. Although these did not compromise the correctness of the algorithm used in the checking tools, they point to the value of machine-checked formalization. In addition, we believe this is the first machine-checked formalization for a realizability algorithm.Comment: 14 pages, 1 figur

Sclerodactyly and Diabetic Complications among Egyptian Adolescent Type 1 Diabetic Patient

BACKGROUND: One of the common complications of diabetic patients is sclerodactyly which is considered as a part of limited joint mobility. AIM: To assess sclerodactyly in adolescent type 1 diabetics and to detect its relation to other diabetic complications. METHODS: Sixty-three diabetics and 60 controls were studied. Clinical, laboratory assessment, ultrasonography of the skin, carotid artery intima-media thickness (cIMT) & renal colour duplex were done for all participants. RESULTS: Sclerodactyly was positive in 12 (19%) of diabetics. Patients with sclerodactyly had a significantly thickened skin compared to patients without sclerodactyly and controls, P = 0.0001. Male diabetics had significantly thickened skin (p = 0.0001). Diabetic patients with sclerodactyly had significant higher systolic blood pressure (p = 0.03), cholesterol (p = 0.05) and triglyceride (p = 0.004) and lower HDL-c (p = 0.04). Skin thickness had a significant positive correlation with age of diabetic patients (p = 0.02), waist/height ratio (p = 0.04), glycosylated hemoglobin (p = 0.03), albumin/creatinine ratio (p = 0.03), and cIMT (p = 0.03). CONCLUSION: Ultrasound easily diagnoses sclerodactyly. Diabetic patients had a high prevalence of sclerodactyly with increased macrovascular and microvascular complications. Sclerodactyly may be a marker for diabetic vascular complications. Frequent follow up of diabetic patients for early detection of sclerodactyly in uncontrolled diabetic patients is recommended. It could be an alarming sign for microalbuminuria, hypertension, hyperlipidaemia and atherosclerosis

Real-Time Synthesis is Hard!

We study the reactive synthesis problem (RS) for specifications given in Metric Interval Temporal Logic (MITL). RS is known to be undecidable in a very general setting, but on infinite words only; and only the very restrictive BRRS subcase is known to be decidable (see D'Souza et al. and Bouyer et al.). In this paper, we precise the decidability border of MITL synthesis. We show RS is undecidable on finite words too, and present a landscape of restrictions (both on the logic and on the possible controllers) that are still undecidable. On the positive side, we revisit BRRS and introduce an efficient on-the-fly algorithm to solve it

Bounded Synthesis of Reactive Programs

Most algorithms for the synthesis of reactive systems focus on the construction of finite-state machines rather than actual programs. This often leads to badly structured, unreadable code. In this paper, we present a bounded synthesis approach that automatically constructs, from a given specification in linear-time temporal logic (LTL), a program in Madhusudan's simple imperative language for reactive programs. We develop and compare two principal approaches for the reduction of the synthesis problem to a Boolean constraint satisfaction problem. The first reduction is based on a generalization of bounded synthesis to two-way alternating automata, the second reduction is based on a direct encoding of the program syntax in the constraint system. We report on preliminary experience with a prototype implementation, which indicates that the direct encoding outperforms the automata approach

Robust Multidimensional Mean-Payoff Games are Undecidable

Mean-payoff games play a central role in quantitative synthesis and verification. In a single-dimensional game a weight is assigned to every transition and the objective of the protagonist is to assure a non-negative limit-average weight. In the multidimensional setting, a weight vector is assigned to every transition and the objective of the protagonist is to satisfy a boolean condition over the limit-average weight of each dimension, e.g., \LimAvg(x_1) \leq 0 \vee \LimAvg(x_2)\geq 0 \wedge \LimAvg(x_3) \geq 0. We recently proved that when one of the players is restricted to finite-memory strategies then the decidability of determining the winner is inter-reducible with Hilbert's Tenth problem over rationals (a fundamental long-standing open problem). In this work we allow arbitrary (infinite-memory) strategies for both players and we show that the problem is undecidable

Copeptin as a Biomarker of Atherosclerosis in Type 1 Diabetic Patients

AIM: To evaluate copeptin as an early marker of atherosclerosis in adolescent type 1 diabetics. METHODS: Sixty-two type 1 diabetic patients and 50 healthy volunteers were enrolled in the study. Serum copeptin, glycosylated haemoglobin (HbA1c), lipid profile, oxidised low-density lipoprotein (OxLDL), urinary albumin/creatinine ratio, carotid intimal medial thickness (cIMT), aortic intimal medial thickness (aIMT) and resistivity index were assessed for all participant in the study. RESULTS: HbA1, albumin/creatinine ratio, lipid profile, OxlDL, copeptin, cIMT and aIMT were significantly higher in diabetic patients. Copeptin was higher in patients with positive cIMT and aIMT. Copeptin correlated with cIMT and aIMT. Stepwise multiple regression analysis found that copeptin correlated with aIMT. ROC curve showed that copeptin had 100 % specificity with aIMT and cIMT and 95.2 and 60,7 sensitivity with aIMT and cIMT respectively. CONCLUSION: Copeptin can be used as a marker for early detection of atherosclerosis of type 1 diabetic patients

Structural Synthesis for GXW Specifications

We define the GXW fragment of linear temporal logic (LTL) as the basis for synthesizing embedded control software for safety-critical applications. Since GXW includes the use of a weak-until operator we are able to specify a number of diverse programmable logic control (PLC) problems, which we have compiled from industrial training sets. For GXW controller specifications, we develop a novel approach for synthesizing a set of synchronously communicating actor-based controllers. This synthesis algorithm proceeds by means of recursing over the structure of GXW specifications, and generates a set of dedicated and synchronously communicating sub-controllers according to the formula structure. In a subsequent step, 2QBF constraint solving identifies and tries to resolve potential conflicts between individual GXW specifications. This structural approach to GXW synthesis supports traceability between requirements and the generated control code as mandated by certification regimes for safety-critical software. Synthesis for GXW specifications is in PSPACE compared to 2EXPTIME-completeness of full-fledged LTL synthesis. Indeed our experimental results suggest that GXW synthesis scales well to industrial-sized control synthesis problems with 20 input and output ports and beyond.Comment: The long (including appendix) version being reviewed by CAV'16 program committee. Compared to the submitted version, one author (out of her wish) is moved to the Acknowledgement. (v2) Corrected typos. (v3) Add an additional remark over environment assumption and easy corner case

Osteopontin for Early Detection of Microvascular and Macrovascular Type 1 Diabetic Complication

AIM: To evaluate the relationship between osteopontin and diabetes complication in type 1 diabetic patient. PATIENTS AND METHODS: Seventy types 1 diabetic and 60 healthy volunteers were studied. Full history, examination, laboratory tests of glycosylated haemoglobin (HbA1c), serum lipids {cholesterol, triglyceride (Tg), high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein – cholesterol (LDL-c)}, oxidised low-density lipoprotein (OxLDL), Osteopontin and urinary microalbuminuria (albumin/creatinine ratio) were done. Image study in the form of a carotid intimal medial thickness (cIMT) and aortic intimal medial thickness (aIMT), renal doppler for resistivity index was also done for all participant included in the study. RESULTS: Urinary albumin/creatinine ratio, lipid profile, osteopontin, cIMT and aIMT were higher in people with diabetes. Osteopontin was higher in people with diabetes with positive microalbuminuria and cIMT. Systolic blood pressure, microalbuminuria and cIMT had a positive correlation with osteopontin in people with diabetes. Stepwise multiple regression analysis showed that osteopontin had a significant correlation with cIMT. Receiver operating characteristic (ROC) curve showed that the cut off value of Osteopontin for detection of cIMT was > 60 with a specificity of 100% and sensitivity 80.5%, while that of albumin/creatinine ratio was > 64 with a specificity of 66.7 and sensitivity of 92.3. CONCLUSION: Osteopontin is higher in type 1 diabetics and is useful for early detection of diabetic microvascular and macrovascular complication

Nitric Oxide Gene Polymorphism is a Risk Factor for Diabetic Nephropathy and Atherosclerosis in Type 1 Diabetic Patients

AIM: To assess the risk factor for diabetic atherosclerosis nephropathy and diabetic nephropathy in type 1 diabetic patients. PATIENTS AND METHODS: Thirty healthy volunteers age and sex-matched and Sixty-five type 1 diabetic patient were in rolled in the study. The mean age of patients was 17.99 ± 2.59 years, mean age of onset of diabetes was 7.00 ± 3.28 years, mean duration of diabetes was 10.91 ± 3.54 years. Glycosylated sex-matched (HbA1c) was assessed in blood samples, serum lipid profile was determined, and serum level of oxidised low-density lipoprotein (OxLDL), and nitric oxide was evaluated by enzyme-linked immunosorbent assay (ELISA) technique. Nitric oxide 894G > T genotype was analysed by (PCR-RFLP) method and confirmed by Sequencing. Assessment of the albumin / creatinine ratio was done in urine samples. Renal Doppler and Carotid intima-media thickness (cIMT) via ultrasound was also performed. RESULTS: OxLDL, lipid profile, albumin/creatinine ratio, cIMT and resistivity index were significantly higher in diabetic patients while nitric oxide was significantly lower. Nitric oxide genotype shows no significant difference between diabetic’s patients and controls. Diabetic patients with homozygous NO had a significantly lower serum level of Nitric oxide, a significantly higher OxLDL, albumin / creatinine ratio and lipid profile. CONCLUSION: diabetic patients are liable for the occurrence of early diabetic nephropathy and atherosclerosis as a result of the presence of low level of nitric oxide. Nitric oxide gene polymorphism 894G > T in diabetic patients is a risk factor for diabetic nephropathy and atherosclerosis

Irisin in Adolescent Type 1 Diabetic Patients and its Relation to Diabetes Control and Atherosclerosis

AIM: The objective of this was to determine the role of irisin in adolescent type 1 diabetes (T1D) patients. METHODS: This study was conducted on 65 patients with T1D and 50 healthy individuals as control group. Serum irisin, glycosylated hemoglobin (HbA1c), lipid profile, oxidized low-density lipoprotein (OxLDL), urinary albumin/creatinine ratio; carotid intimal medial thickness (cIMT), and aortic intimal medial thickness (aIMT) were evaluated for all participant. RESULTS: HbA1c, lipid profile, albumin/creatinine ratio, OxLDL, irisin, aIMT and cIMT were significantly higher in diabetic patients. Irisin had a positive correlation with age of diabetic patients, onset of diabetes, mid arm circumference, waist/height ratio, body mass index, HbA1c, and cIMT. CONCLUSION: Irisin is a marker for detection of diabetes control and early detection of subclinical atherosclerosis. Irisin had a relation with obesity