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Gaurav Sinha

Publications and source records attributed to Gaurav Sinha.

20 records · Page 2Linked to original sources

Dis-entangling Mixture of Interventions on a Causal Bayesian Network Using Aggregate Observations

We study the problem of separating a mixture of distributions, all of which come from interventions on a known causal bayesian network. Given oracle access to marginals of all distributions resulting from interventions on the network, and estimates of marginals from the mixture distribution, we want to recover the mixing proportions of different mixture components. We show that in the worst case, mixing proportions cannot be identified using marginals only. If exact marginals of the mixture distribution were known, under a simple assumption of excluding a few distributions from the mixture, we show that the mixing proportions become identifiable. Our identifiability proof is constructive and gives an efficient algorithm recovering the mixing proportions exactly. When exact marginals are not available, we design an optimization framework to estimate the mixing proportions. Our problem is motivated from a real-world scenario of an e-commerce business, where multiple interventions occur at a given time, leading to deviations in expected metrics. We conduct experiments on the well known publicly available ALARM network and on a proprietary dataset from a large e-commerce company validating the performance of our method.

cs.LG↗

Reconstruction of depth-3, top fan-in two circuits over characteristic zero fields

Reconstruction of arithmetic circuits has been heavily studied in the past few years and has connections to proving lower bounds and deterministic identity testing. In this paper we present a polynomial time randomized algorithm for reconstructing $ΣΠΣ(2)$ circuits over $\mathbb{F}$ ($char(\mathbb{F})=0$), i.e. depth$-3$ circuits with fan-in $2$ at the top addition gate and having coefficients from a field of characteristic $0$. The algorithm needs only a blackbox query access to the polynomial $f \in \mathbb{F}[x_1,\ldots, x_n]$ of degree $d$, computable by a $ΣΠΣ(2)$ circuit $C$. In addition, we assume that "simple rank" of this polynomial (essential number of variables after removing gcd of the two multiplication gates) is bigger than a constant. Our algorithm runs in time $poly(n, d)$ and returns an equivalent $ΣΠΣ(2)$ circuit(with high probability). The problem of reconstructing $ΣΠΣ(2)$ circuits over finite fields was first proposed by Shpilka in [24]. The generalization to $ΣΠΣ(k)$ circuits, $k = O(1)$ (over finite fields) was addressed by Karnin and Shpilka in [15]. The techniques in these previous involve iterating over all objects of certain kinds over the ambient field and thus running time depends on size of the field $\mathbb{F}$. Their reconstruction algorithm uses lower bounds on the lengths of Linear Locally Decodable Codes with $2$ queries. In our settings, such ideas immediately pose a problem and we need new ideas to handle the case of the characteristic $0$ field $\mathbb{F}$. Our main techniques are based on the use of Quantitative Syslvester Gallai Theorems from the work of Barak et.al. [3] to find a small collection of subspaces to project onto. The heart of our paper lies in subtle applications of Quantitative Sylvester Gallai theorems to prove why projections w.r.t. these subspaces can be glued.

cs.DS↗