A satisfiability procedure for quantified Boolean formulae

We present a satisfiability tester QSAT for quantified Boolean formulae and a restriction of QSAT to unquantified conjunctive normal form formulae. QSAT makes use of procedures which replace subformulae of a formula by equivalent formulae. By a sequence of such replacements, the original formula can be simplified to or . It may also be necessary to transform the original formula to generate a subformula to replace. eliminates collections of variables from an unquantified clause form formula until all variables have been eliminated. QSAT and can be applied to hardware verification and symbolic model checking. Results of an implementation of are described, as well as some complexity results for QSAT and . QSAT runs in linear time on a class of quantified Boolean formulae related to symbolic model checking. We present the class of “long and thin” unquantified formulae and give evidence that this class is common in applications. We also give theoretical and empirical evidence that is often faster than Davis and Putnam-type satisfiability checkers and ordered binary decision diagrams (OBDDs) on this class of formulae. We give an example where is exponentially faster than BDDs

Reply to: Mobility overestimation in MoS2_2 transistors due to invasive voltage probes

In this reply, we include new experimental results and verify that the observed non-linearity in rippled-MoS$_2$ (leading to mobility kink) is an intrinsic property of a disordered system, rather than contact effects (invasive probes) or other device issues. Noting that Peng Wu's hypothesis is based on a highly ordered ideal system, transfer curves are expected to be linear, and the carrier density is assumed be constant. Wu's model is therefore oversimplified for disordered systems and neglects carrier-density dependent scattering physics. Thus, it is fundamentally incompatible with our rippled-MoS$_2$, and leads to the wrong conclusion

Efficacy and safety of low-dose IL-2 in the treatment of systemic lupus erythematosus: A randomised, double-blind, placebo-controlled trial

Objectives Open-labelled clinical trials suggested that low-dose IL-2 might be effective in treatment of systemic lupus erythematosus (SLE). A double-blind and placebocontrolled trial is required to formally evaluate the safety and efficacy of low-dose IL-2 therapy. Methods A randomised, double-blind and placebocontrolled clinical trial was designed to treat 60 patients with active SLE. These patients received either IL-2 (n=30) or placebo (n=30) with standard treatment for 12 weeks, and were followed up for additional 12 weeks. IL-2 at a dose of 1 million IU or placebo was administered subcutaneously every other day for 2 weeks and followed by a 2-week break as one treatment cycle. The primary endpoint was the SLE Responder Index-4 (SRI-4) at week 12. The secondary endpoints were other clinical responses, safety and dynamics of immune cell subsets. Results At week 12, the SRI-4 response rates were 55.17% and 30.00% for IL-2 and placebo, respectively (p=0.052). At week 24, the SRI-4 response rate of IL-2 group was 65.52%, compared with 36.67% of the placebo group (p=0.027). The primary endpoint was not met at week 12. Low-dose IL-2 treatment resulted in 53.85% (7/13) complete remission in patients with lupus nephritis, compared with 16.67% (2/12) in the placebo group (p=0.036). No serious infection was observed in the IL-2 group, but two in placebo group. Besides expansion of regulatory T cells, low-dose IL-2 may also sustain cellular immunity with enhanced natural killer cells. Conclusions Low-dose IL-2 might be effective and tolerated in treatment of SThe work was supported by the National Natural Science Foundation of China (31530020,31570880,81471601,81601417 and 81701598), Peking-Tsinghua Center for Life Sciences to ZG LI, Beijing Sci-Tech Committee Z171100000417007,Clinical Medicine Plus X-Young Scholars Project of Peking University (PKU2019LCXQ013) supported by the Fundamental Research Funds for the Central Universities, Beijing Nova Program Z171100001117025, National Key Research and Development Program of China (2017YFC0909003 to DY), BellberryViertel Senior Medical Research Fellowship to DY and Beijing SL PHARM

Generator-based verification

To prove system correctness, assumptions made in verifying a block must be cleared by verifying that the block’s environment guarantees them. Conversely, guarantees enforced by a block may be used as assumptions for its environment. Block level interface specifications thus serve as both assumptions and guarantees in compositional verification. Traditionally, such specifications have been represented as monitors or checkers. In this paper, we propose an alternative representation using generators. Novel algorithms are presented for simulation and formal verification. We argue that for simulation, representation as a generator can be more efficient than as a checker – both asymptotically and practically. We also identify a subset of generators that can be efficiently handled using formal techniques. Experimental results are given for some benchmark examples and industrial case studies. 1

Efficient First-Order Semantic Deduction Techniques

Mathematical logic formalizes the process of mathematical reasoning. For centuries, it has been a dream of mathematicians to do mathematical reasoning mechanically. In the TPTP library, one finds thousands of problems from various domains of mathematics such as group theory, number theory, set theory, etc. Many of these problems can now be solved with state of the art automated theorem provers. Theorem proving also has applications in artificial intelligence and formal verification. As a formal method, theorem proving has been used to verify the correctness of various hardware and software designs. In this thesis, we propose a novel first-order theorem proving strategy -- ordered semantic hyper linking (OSHL). OSHL is an instance-based theorem proving strategy. It proves first-order unsatisfiability by generating instances of first-order clauses and proving the set of instances to be propositionally unsatisfiable. OSHL can use semantics, i.e. domain information, to guide its search. OS..

Kinematic Manipulation of Molecular Chains Subject to Rigid Constraints

We present algorithms for kinematic manipulation of molecular chains subject to fixed bond lengths and bond angles. They are useful for calculating conformations of a molecule subject to geometric constraints, such as those derived from two-dimensional NMR experiments. Other applications include searching out the full range of conformations available to a molecule such as cyclic configurations. We make use of results from robot kinematics and recently developed algorithms for solving polynomial systems. In particular, we model the molecule as a serial chain using the Denavit-Hartenberg formulation and reduce these problems to inverse kinematics of a serial chain. We also highlight the relationship between molecular embedding problems and inverse kinematics. As compared to earlier methods, the main advantages of the kinematic formulation are its generality to all molecular chains without any restrictions on the geometry and efficiency in terms of performance. The algorithms give us real..

Situation Calculus with Aspect

In this paper, we describe situation calculus with aspect, which is an extension of the classical situation calculus. The new approach allows efficient representation of the frame axioms and partially ordered plans. In S.C. with aspect, fluents and actions are associated with aspects. The frame axioms are replaced by axioms that describe the interference relation between aspects. A plan is represented as multiple sequences of actions applied on different aspects. We believe that the new representation will improve the efficiency of logic based planners and facilitate the analysis of total order and partial order planning techniques. 1 Introduction In this paper, we propose some extensions to the classical situation calculus[MH69]. We call the new representation scheme situation calculus with aspect. It classifies fluents and actions by their "aspects", and allows a more flexible representation of planning domain theories. Using S.C. with aspect, we can efficiently represent the frame ..