A Unified Framework for Multi-Agent Agreement

Multi-Agent Agreement problems (MAP) - the ability of a population of agents to search out and converge on a common state - are central issues in many multi-agent settings, from distributed sensor networks, to meeting scheduling, to development of norms, conventions, and language. While much work has been done on particular agreement problems, no unifying framework exists for comparing MAPs that vary in, e.g., strategy space complexity, inter-agent accessibility, and solution type, and understanding their relative complexities. We present such a unification, the Distributed Optimal Agreement Framework, and show how it captures a wide variety of agreement problems. To demonstrate DOA and its power, we apply it to two well-known MAPs: convention evolution and language convergence. We demonstrate the insights DOA provides toward improving known approaches to these problems. Using a careful comparative analysis of a range of MAPs and solution approaches via the DOA framework, we identify a single critical differentiating factor: how accurately an agent can discern other agent.s states. To demonstrate how variance in this factor influences solution tractability and complexity we show its effect on the convergence time and quality of Particle Swarm Optimization approach to a generalized MAP

Single-agent PARP inhibitors for the treatment of patients with BRCA-mutated HER2-negative metastatic breast cancer: a systematic review and meta-analysis

Single-agent poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have been approved as the first targeted therapy available for patients with BRCA-mutated HER2-negative metastatic breast cancer. This meta-analysis aimed to better evaluate activity, efficacy and safety of single-agent PARPi in this population. A systematic search of Medline, Embase and conference proceedings up to 31 January 2018 was conducted to identify randomised controlled trials (RCTs) investigating single-agent PARPi versus monochemotherapy in patients with BRCA-mutated HER2-negative metastatic breast cancer. Using the random-effect model, we calculated summary risk estimates (pooled HR and OR with 95% CI) for progression-free survival (PFS), overall survival (OS), objective response rate (ORR), any grade and grade 3-4 adverse events (AEs), treatment discontinuation rate and time to deterioration in quality of life (QoL). Two RCTs (n=733) were included. As compared with monochemotherapy, single-agent PARPi significantly improved PFS (HR 0.56(95% CI 0.45 to 0.70)) and ORR (OR 4.15 (95% CI 2.82 to 6.10)), with no difference in OS (HR 0.82 (95% CI 0.64 to 1.05)). Single-agent PARPi significantly increased risk of anaemia and any grade headache, but reduced risk of neutropenia and any grade palmar-plantar erythrodysesthesia syndrome as compared with monochemotherapy. No significant differences in other AEs and treatment discontinuation rate were observed. Patients treated with PARPi experienced a significant delayed time to QoL deterioration (HR 0.40 (95% CI 0.29 to 0.54)). Single-agent PARPi showed to be an effective, well tolerated and useful treatment in maintaining QoL of patients with BRCA-mutated HER2-negative metastatic breast cancer

Adversarial Brokerage in Residential Real Estate Transactions: The Impact of Separate Buyer Representation

Although substantial research effort has been directed to the examination of optimal search and pricing behavior under traditional brokerage arrangements, market outcomes under conditions of undisclosed subagency and buyer representation have not been fully explored. This study applies the legal and economic theory of agency to real estate markets with cooperating brokers. The existence of cooperating brokers acting as subagents of the seller with the buyer’s full knowledge does not change the buyer’s and seller’s net payoffs relative to the single-agent case. However, when the buyer mistakenly believes that the cooperating broker/subagent is acting as his agent in negotiations, there may be informational gains that result in a higher selling price and a higher payoff to the seller at the expense of the buyer. The analysis indicates that buyer brokers may be a potential solution to this agency problem. When both parties to a real estate transaction have separate representation, their net payoffs are shown to be higher and the sales price lower than under traditional brokerage arrangements. The result is dependent on several factors, including: market conditions, relative bargaining power of the parties, method of broker compensation, and disclosure of the status of the buyer broker.

Chaotic Quantum Double Delta Swarm Algorithm using Chebyshev Maps: Theoretical Foundations, Performance Analyses and Convergence Issues

Quantum Double Delta Swarm (QDDS) Algorithm is a new metaheuristic algorithm inspired by the convergence mechanism to the center of potential generated within a single well of a spatially co-located double-delta well setup. It mimics the wave nature of candidate positions in solution spaces and draws upon quantum mechanical interpretations much like other quantum-inspired computational intelligence paradigms. In this work, we introduce a Chebyshev map driven chaotic perturbation in the optimization phase of the algorithm to diversify weights placed on contemporary and historical, socially-optimal agents' solutions. We follow this up with a characterization of solution quality on a suite of 23 single-objective functions and carry out a comparative analysis with eight other related nature-inspired approaches. By comparing solution quality and successful runs over dynamic solution ranges, insights about the nature of convergence are obtained. A two-tailed t-test establishes the statistical significance of the solution data whereas Cohen's d and Hedge's g values provide a measure of effect sizes. We trace the trajectory of the fittest pseudo-agent over all function evaluations to comment on the dynamics of the system and prove that the proposed algorithm is theoretically globally convergent under the assumptions adopted for proofs of other closely-related random search algorithms.Comment: 27 pages, 4 figures, 19 table

Endocrine‐based treatments in clinically‐relevant subgroups of hormone receptor‐positive/her2‐negative metastatic breast cancer: Systematic review and meta‐analysis

A precise assessment of the efficacy of first-/second-line endocrine therapies (ET) +/- target therapies (TT) in clinically-relevant subgroups of hormone receptor-positive (HR+)/HER2-negative metastatic breast cancer (MBC) has not yet been conducted. To improve our current knowledge and support clinical decision-making, we thus conducted a systematic literature search to identify all first-/second-line phase II/III randomized clinical trials (RCT) of currently approved or most promising ET +/- TT. Then, we performed a meta-analysis to assess progression-free (PFS) and/or overall survival (OS) benefit in several clinically-relevant prespecified subgroups. Thirty-five RCT were included (17,595 patients). Pooled results show significant reductions in the risk of relapse or death of 26-41% and 12-27%, respectively, depending on the clinical subgroup. Combination strategies proved to be more effective than single-agent ET (PFS hazard ratio (HR) range for combinations: 0.60-0.65 vs. HR range for single agent ET: 0.59-1.37; OS HR range for combinations: 0.74-0.87 vs. HR range for single agent ET: 0.68-0.98), with CDK4/6-inhibitors(i) + ET being the most effective regimen. Single agent ET showed comparable efficacy with ET+TT combinations in non-visceral (p = 0.63) and endocrine sensitive disease (p = 0.79), while mTORi-based combinations proved to be a valid therapeutic option in endocrine-resistant tumors, as well as PI3Ki + ET in PIK3CA-mutant tumors. These results strengthen international treatment guidelines and can aid therapeutic decision-making

Endocrine‐based treatments in clinically‐relevant subgroups of hormone receptor‐positive/HER2‐negative metastatic breast cancer: systematic review and meta‐analysis

A precise assessment of the efficacy of first‐/second‐line endocrine therapies (ET) ± target therapies (TT) in clinically‐relevant subgroups of hormone receptor‐positive (HR+)/HER2‐negative metastatic breast cancer (MBC) has not yet been conducted. To improve our current knowledge and support clinical decision‐making, we thus conducted a systematic literature search to identify all first‐/second‐line phase II/III randomized clinical trials (RCT) of currently approved or most promising ET ± TT. Then, we performed a meta‐analysis to assess progression‐free (PFS) and/or overall survival (OS) benefit in several clinically‐relevant prespecified subgroups. Thirty‐five RCT were included (17,595 patients). Pooled results show significant reductions in the risk of relapse or death of 26–41% and 12–27%, respectively, depending on the clinical subgroup. Combination strategies proved to be more effective than single‐agent ET (PFS hazard ratio (HR) range for combinations: 0.60–0.65 vs. HR range for single agent ET: 0.59–1.37; OS HR range for combinations: 0.74–0.87 vs. HR range for single agent ET: 0.68–0.98), with CDK4/6‐inhibitors(i) + ET being the most effective regimen. Single agent ET showed comparable efficacy with ET+TT combinations in nonvisceral (p = 0.63) and endocrine sensitive disease (p = 0.79), while mTORi‐based combinations proved to be a valid therapeutic option in endocrine‐resistant tumors, as well as PI3Ki + ET in PIK3CA‐mutant tumors. These results strengthen international treatment guidelines and can aid therapeutic decision‐making

Developing Internet Agents: A Tutorial Using Visual Basic 6.0

An agent is someone or something authorized to “act on behalf of” another person. In professional sports, for example, an athlete’s agent may be authorized to negotiate the athlete’s contract, but may or may not be authorized to accept the terms of a contract. Similarly, an Internet agent acts on behalf of a person who wishes to conduct some activity utilizing the Internet. The capabilities and authority invested in such an agent are at the discretion of the person it represents. Typically Internet agents perform search and data collection activities. They may or may not have authority to negotiate or conduct purchase or sale transactions. Internet agents have varying levels of sophistication including lifespan, error detection and recovery, data validation, and embedded intelligence (Kauffman et al. 1999). A simple Internet agent, for example, may contact a single Web site (e.g., Amazon.com), extract a single fact (e.g., the price of a specified book) and report that fact to the user. A more sophisticated Internet agent may contact multiple Web sites (e.g., Amazon.com and BarnesAndNoble.com), track facts for several days or weeks (e.g., prices of a basket of books), record those facts for later analysis (e.g., in a database), and conduct transactions (e.g., purchase a subset of the basket of books when prices and availability meet given criteria). Today’s component-based, rapid application development environments allow individuals with very limited programming experience to build relatively sophisticated Internet agents without lengthy courses in Internet protocols or advanced programming techniques. Using development environments such as Visual Basic 6.0, simple but non-trivial Internet agents can be specified using a handful of components and a few dozen lines of code. The following sections present a single example illustrating the most rudimentary capabilities needed to create an Internet agent. This agent merely retrieves the raw HTML from a specified URL. A more complete tutorial, available at http://www.internet- technology.org/tutorials/agents/visualbasic/march includes examples of more sophisticated agents having more useful capabilities. These include following links, extracting and interpreting the data, and storing that data in a database for later analysis

The pine wood nematode, Bursaphelenchus xylophilus, in Portugal: possible introductions and spread routes of a serious biological invasion revealed by molecular methods

The pine wood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), is a major world-wide pathogen and pest of pine, with impacts on forest health, natural ecosystem stability and international trade. In Portugal, PWN was first diagnosed in 1999, the first occurrence also for Europe. The disease was recently detected on the island ofMadeira and in northern Spain. In an attempt to search for more reliable and robust molecular markers that enable the study of intraspecific variability of B. xylophilus from different geographic locations, the intergenic spacer (IGS) region of the 5S rRNA gene and inter-simple sequence repeats (ISSR) analysis were used to determine the genetic relationships among 43 B. xylophilus isolates from Portugal, China, Japan, South Korea and USA. IGS sequence analysis showed that this region can only be used to establish interspecific relationships, since no differences were detected among Portuguese isolates from different geographic locations. Fingerprints obtained with ISSR show high genetic variability among Portuguese isolates, except for the ones obtained prior to 2008. The ISSR dendrogram suggests the spread of the disease inside continental Portugal and to Madeira. Until 2008, B. xylophilus populations found in continental Portugal showed low genetic diversity, pointing to a single introduction, probably from Asia, whereas recent populations from continental Portugal (2009-2010) and Madeira show high genetic diversity, suggesting multiple introductions from different origins