11 research outputs found
Causal Interpretation of Self-Attention in Pre-Trained Transformers
We propose a causal interpretation of self-attention in the Transformer
neural network architecture. We interpret self-attention as a mechanism that
estimates a structural equation model for a given input sequence of symbols
(tokens). The structural equation model can be interpreted, in turn, as a
causal structure over the input symbols under the specific context of the input
sequence. Importantly, this interpretation remains valid in the presence of
latent confounders. Following this interpretation, we estimate conditional
independence relations between input symbols by calculating partial
correlations between their corresponding representations in the deepest
attention layer. This enables learning the causal structure over an input
sequence using existing constraint-based algorithms. In this sense, existing
pre-trained Transformers can be utilized for zero-shot causal-discovery. We
demonstrate this method by providing causal explanations for the outcomes of
Transformers in two tasks: sentiment classification (NLP) and recommendation.Comment: 37th Conference on Neural Information Processing Systems (NeurIPS
2023). arXiv admin note: text overlap with arXiv:2210.1062
From Temporal to Contemporaneous Iterative Causal Discovery in the Presence of Latent Confounders
We present a constraint-based algorithm for learning causal structures from
observational time-series data, in the presence of latent confounders. We
assume a discrete-time, stationary structural vector autoregressive process,
with both temporal and contemporaneous causal relations. One may ask if
temporal and contemporaneous relations should be treated differently. The
presented algorithm gradually refines a causal graph by learning long-term
temporal relations before short-term ones, where contemporaneous relations are
learned last. This ordering of causal relations to be learnt leads to a
reduction in the required number of statistical tests. We validate this
reduction empirically and demonstrate that it leads to higher accuracy for
synthetic data and more plausible causal graphs for real-world data compared to
state-of-the-art algorithms.Comment: Proceedings of the 40-th International Conference on Machine Learning
(ICML), 202
Quantum Conserved Currents in Affine Toda Theories
We study the renormalization and conservation at the quantum level of
higher-spin currents in affine Toda theories with particular emphasis on the
nonsimply-laced cases. For specific examples, namely the spin-3 current for the
and theories, we prove conservation to all-loop order,
thus establishing the existence of factorized S-matrices. For these theories,
as well as the simply-laced theory, we compute one-loop corrections
to the corresponding higher-spin charges and study charge conservation for the
three-particle vertex function. For the theory we show that
although the current is conserved, anomalous threshold singularities spoil the
conservation of the corresponding charge for the on-shell vertex function,
implying a breakdown of some of the bootstrap procedures commonly used in
determining the exact S-matrix.Comment: 19 page
Quantum Conserved Currents in Supersymmetric Toda Theories
We consider supersymmetric Toda theories which admit a fermionic
untwisted affine extension, i.e. the systems based on the ,
and superalgebras. We construct the superspace Miura trasformations
which allow to determine the W-supercurrents of the conformal theories and we
compute their renormalized expressions. The analysis of the renormalization and
conservation of higher-spin currents is then performed for the corresponding
supersymmetric massive theories. We establish the quantum integrability of
these models and show that although their Lagrangian is not hermitian, the
masses of the fundamental particles are real, a property which is maintained by
one-loop corrections. The spectrum is actually much richer, since the theories
admit solitons. The existence of quantum conserved higher-spin charges implies
that elastic, factorized S-matrices can be constructed.Comment: 35 pages, IFUM 426/F
KINETIC IONIZATION WAVES IN A CHARGE IN NEON
A positive pole of a glow discharge in inert gases in considered in the paper aiming at the complex theoretical and experimental investigation of a longitudinal-homogeneous and stratified pole. During the investigation sound and optical methods for the investigation of a low-temperature plasma, solution numerical methods for intergrodifferential equations have been used. As a result the methodology for the self-coordinate calculation of characteristics of a longitudinal-homogeneous positive pole has been developed and realized. The kinetic theory for the formation of strats near a lower boundary of their existence on current has been developed. Mechanisms of the discharge stratification have been cleared up. The theoretical and experimental results are in good coordination, that gives the possibilities of the qualitative description of various types of discharges at low pressureAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio
Actinobacillus actinomycetemcomitans Serotype b Lipopolysaccharide Mediates Coaggregation with Fusobacterium nucleatum
Purified Actinobacillus actinomycetemcomitans serotype b lipopolysaccharide (LPS) was found to be able to bind Fusobacterium nucleatum cells and to inhibit binding of F. nucleatum to A. actinomycetemcomitans serotype b. Sugar binding studies showed that the requirements for binding of A. actinomycetemcomitans serotype b LPS to the F. nucleatum lectin are the presence of a metal divalent ion, an axial free hydroxyl group at position 4, and free equatorial hydroxyl groups at positions 3 and 6 of d-galactose, indicating that the β-N-acetyl-d-galactosamine in the serotype b LPS trisaccharide repeating unit is the monosaccharide residue recognized by the F. nucleatum lectin. These data strongly suggest that A. actinomycetemcomitans serotype b LPS is one of the receptors responsible for the lactose-inhibitable coaggregation of A. actinomycetemcomitans to fusobacteria