Cause-Effect Association between Event Pairs in Event Datasets

Causal discovery from observational data has been intensely studied across fields of study. In this paper, we consider datasets involving irregular occurrences of various types of events over the timeline. We propose a suite of scores and related algorithms for estimating the cause-effect association between pairs of events from such large event datasets. In particular, we introduce a general framework and the use of conditional intensity rates to characterize pairwise associations between events. Discovering such potential causal relationships is critical in several domains, including health, politics and financial analysis. We conduct an experimental investigation with synthetic data and two real-world event datasets, where we evaluate and compare our proposed scores using assessments from human raters as ground truth. For a political event dataset involving interaction between actors, we show how performance could be enhanced by enforcing additional knowledge pertaining to actor identities.

Hawkes process modeling of COVID-19 with mobility leading indicators and spatial covariates

Hawkes processes are used in machine learning for event clustering and causal inference, while they also can be viewed as stochastic versions of popular compartmental models used in epidemiology. Here we show how to develop accurate models of COVID-19 transmission using Hawkes processes with spatial-temporal covariates. We model the conditional intensity of new COVID-19 cases and deaths in the U.S. at the county level, estimating the dynamic reproduction number of the virus within an EM algorithm through a regression on Google mobility indices and demographic covariates in the maximization step. We validate the approach on short-term forecasting tasks, showing that the Hawkes process outperforms several benchmark models currently used to track the pandemic, including an ensemble approach and a SEIR-variant. We also investigate which covariates and mobility indices are most important for building forecasts of COVID-19 in the U.S.

Parameter Estimation of the Temporal Point Process Model through the Bayesian Approach (Case Study : Malaria Disease Data from Wahidin Hospital in Makassar City)

Penelitian ini bertujuan mengestimasi parameter melalui pendekatan Bayesian dari model temporal point process. Paramater intensitas bersyarat model tersebut dipandang sebagai suatu renewal process yang selanjutnya digunakan melalui pendekatan Squared Error Loss Function (SELF). Parameter intensitas bersyarat model temporal point process diestimasi menggunakan metode maximum likelihood estimation melalui persamaan likelihood point process. Selain itu, penelitian ini mengkaji metode estimasi maksimum likelihood dan metode Bayes untuk menganalis fungsi resiko dari hasil penaksir parameter intensitas bersyarat. Pada aplikasi estimasi parameter ini, studi kasus yang digunakan adalah menganalisa data orang yang terkena penyakit malaria yang datanya berasal dari Rumah Sakit Wahidin Kota Makassar. Studi kasus tersebut menghasilkan nilai yang merupakan nilai resiko penaksir MLE yang lebih tinggi dibandingkan dengan menggunakan Metode Bayes sedangkan nilai merupakan hasil nilai resiko dari penaksir MLE yang lebih kecil dibandingkan dengan menggunakan Metode Bayes. This study parameter estimation of conditional intensity with temporal point process model by Bayesian approach. The conditional intensity with temporal point process model derived as a renewal process where inter event time is defined as its random variable. Squared Error Loss Function (SELF) approach is used to estimate the parameter of conditional intensity with temporal point process model which is happened as a renewal process using Bayesian. The other outlines of this paper is to determine the Risk Function as the result of estimation of conditional intensity by Bayesian and by Maximum likelihood Estimation (MLE). The application taking an analysis of Malaria at a place, which is properly conclude that the estimation using MLE method is more risky than the Bayesian it self.

Context-Aware Superpixel and Bilateral Entropy—Image Coherence Induces Less Entropy

Superpixel clustering is one of the most popular computer vision techniques that aggregates coherent pixels into perceptually meaningful groups, taking inspiration from Gestalt grouping rules. However, due to brain complexity, the underlying mechanisms of such perceptual rules are unclear. Thus, conventional superpixel methods do not completely follow them and merely generate a flat image partition rather than hierarchical ones like a human does. In addition, those methods need to initialize the total number of superpixels, which may not suit diverse images. In this paper, we first propose context-aware superpixel (CASP) that follows both Gestalt grouping rules and the top-down hierarchical principle. Thus, CASP enables to adapt the total number of superpixels to specific images automatically. Next, we propose bilateral entropy, with two aspects conditional intensity entropy and spatial occupation entropy, to evaluate the encoding efficiency of image coherence. Extensive experiments demonstrate CASP achieves better superpixel segmentation performance and less entropy than baseline methods. More than that, using Pearson’s correlation coefficient, a collection of data with a total of 120 samples demonstrates a strong correlation between local image coherence and superpixel segmentation performance. Our results inversely support the reliability of above-mentioned perceptual rules, and eventually, we suggest designing novel entropy criteria to test the encoding efficiency of more complex patterns.

Patent Citation Dynamics Modeling via Multi-Attention Recurrent Networks

Modeling and forecasting forward citations to a patent is a central task for the discovery of emerging technologies and for measuring the pulse of inventive progress. Conventional methods for forecasting these forward citations cast the problem as analysis of temporal point processes which rely on the conditional intensity of previously received citations. Recent approaches model the conditional intensity as a chain of recurrent neural networks to capture memory dependency in hopes of reducing the restrictions of the parametric form of the intensity function. For the problem of patent citations, we observe that forecasting a patent's chain of citations benefits from not only the patent's history itself but also from the historical citations of assignees and inventors associated with that patent. In this paper, we propose a sequence-to-sequence model which employs an attention-of-attention mechanism to capture the dependencies of these multiple time sequences. Furthermore, the proposed model is able to forecast both the timestamp and the category of a patent's next citation. Extensive experiments on a large patent citation dataset collected from USPTO demonstrate that the proposed model outperforms state-of-the-art models at forward citation forecasting.