Tardos fingerprinting is better than we thought

We review the fingerprinting scheme by Tardos and show that it has a much better performance than suggested by the proofs in Tardos' original paper. In particular, the length of the codewords can be significantly reduced. First we generalize the proofs of the false positive and false negative error probabilities with the following modifications: (1) we replace Tardos' hard-coded numbers by variables and (2) we allow for independently chosen false positive and false negative error rates. It turns out that all the collusion-resistance properties can still be proven when the code length is reduced by a factor of more than 2. Second, we study the statistical properties of the fingerprinting scheme, in particular the average and variance of the accusations. We identify which colluder strategy forces the content owner to employ the longest code. Using a gaussian approximation for the probability density functions of the accusations, we show that the required false negative and false positive error rate can be achieved with codes that are a factor 2 shorter than required for rigid proofs. Combining the results of these two approaches, we show that the Tardos scheme can be used with a code length approximately 5 times shorter than in the original construction.Comment: Modified presentation of result

Optimal Detection of Faulty Traffic Sensors Used in Route Planning

In a smart city, real-time traffic sensors may be deployed for various applications, such as route planning. Unfortunately, sensors are prone to failures, which result in erroneous traffic data. Erroneous data can adversely affect applications such as route planning, and can cause increased travel time. To minimize the impact of sensor failures, we must detect them promptly and accurately. However, typical detection algorithms may lead to a large number of false positives (i.e., false alarms) and false negatives (i.e., missed detections), which can result in suboptimal route planning. In this paper, we devise an effective detector for identifying faulty traffic sensors using a prediction model based on Gaussian Processes. Further, we present an approach for computing the optimal parameters of the detector which minimize losses due to false-positive and false-negative errors. We also characterize critical sensors, whose failure can have high impact on the route planning application. Finally, we implement our method and evaluate it numerically using a real-world dataset and the route planning platform OpenTripPlanner.Comment: Proceedings of The 2nd Workshop on Science of Smart City Operations and Platforms Engineering (SCOPE 2017), Pittsburgh, PA USA, April 2017, 6 page

The number of negative modes of the oscillating bounces

The spectrum of small perturbations about oscillating bounce solutions recently discussed in the literature is investigated. Our study supports quite intuitive and expected result: the bounce with N nodes has exactly N homogeneous negative modes. Existence of more than one negative modes makes obscure the relation of these oscillating bounce solutions to the false vacuum decay processes.Comment: LaTex, 6 pages, including 3 figure

What's on your mind? Recent advances in memory detection using the concealed information test

Lie detectors can be applied in a wide variety of settings. But this advantage comes with a considerable cost: False positives. The applicability of the Concealed Information Test (CIT) is More limited, yet when it can be applied, the risk of false accusations can be set a priori at a very low level. The CIT assesses the recognition of; critical information that is known only by the examiners and the culprit, for example, the face a an accomplice. Large effects are Obtained with the CIT, whether combined with peripheral, brain, or Motor responses. We see three important challenges for the CIT. First, the false negative rate Of the CIT can be substantial, particularly under :realistic circumstantes. A possible solution Seems to restrict the CIT to highly Salient details. Second, there exist effective faking strategies. Future research will tell whether faking can be detected or even prevented (e.g., Using Overt measures). Third, recognition of critical crime detail's does not necessarily result from criminal activity. It is therefore important to properly embed the CIT in the investigative process, While taking care when drawing conclusions from the test outcome (recognition, not guilt)