136 research outputs found
Criticality in Translation-Invariant Parafermion Chains
In this work we numerically study critical phases in translation-invariant
parafermion chains with both nearest- and next-nearest-neighbor
hopping terms. The model can be mapped to a spin model with
nearest-neighbor couplings via a generalized Jordan-Wigner transformation and
translation invariance ensures that the spin model is always self-dual. We
first study the low-energy spectrum of chains with only nearest-neighbor
coupling, which are mapped onto standard self-dual clock models.
For we match the numerical results to the known conformal field
theory(CFT) identification. We then analyze in detail the phase diagram of a
chain with both nearest and next-nearest neighbor hopping and six
critical phases with central charges being , 1 or 2 are found. We find
continuous phase transitions between and phases, while the phase
transition between and is conjectured to be of
Kosterlitz-Thouless type.Comment: published versio
Topology and Criticality in Resonating Affleck-Kennedy-Lieb-Tasaki loop Spin Liquid States
We exploit a natural Projected Entangled-Pair State (PEPS) representation for
the resonating Affleck-Kennedy-Lieb-Tasaki loop (RAL) state. By taking
advantage of PEPS-based analytical and numerical methods, we characterize the
RAL states on various two-dimensional lattices. On square and honeycomb
lattices, these states are critical since the dimer-dimer correlations decay as
a power law. On kagome lattice, the RAL state has exponentially decaying
correlation functions, supporting the scenario of a gapped spin liquid. We
provide further evidence that the RAL state on the kagome lattice is a
spin liquid, by identifying the four topological sectors and
computing the topological entropy. Furthermore, we construct a one-parameter
family of PEPS states interpolating between the RAL state and a short-range
Resonating Valence Bond state and find a critical point, consistent with the
fact that the two states belong to two different phases. We also perform a
variational study of the spin-1 kagome Heisenberg model using this
one-parameter PEPS.Comment: 10 pages, 14 figures, published versio
Chiral projected entangled-pair state with topological order
We show that projected entangled-pair states (PEPS) can describe chiral
topologically ordered phases. For that, we construct a simple PEPS for spin-1/2
particles in a two-dimensional lattice. We reveal a symmetry in the local
projector of the PEPS that gives rise to the global topological character. We
also extract characteristic quantities of the edge conformal field theory using
the bulk-boundary correspondence.Comment: 11 pages, 7 figure
Generating Synergistic Formulaic Alpha Collections via Reinforcement Learning
In the field of quantitative trading, it is common practice to transform raw
historical stock data into indicative signals for the market trend. Such
signals are called alpha factors. Alphas in formula forms are more
interpretable and thus favored by practitioners concerned with risk. In
practice, a set of formulaic alphas is often used together for better modeling
precision, so we need to find synergistic formulaic alpha sets that work well
together. However, most traditional alpha generators mine alphas one by one
separately, overlooking the fact that the alphas would be combined later. In
this paper, we propose a new alpha-mining framework that prioritizes mining a
synergistic set of alphas, i.e., it directly uses the performance of the
downstream combination model to optimize the alpha generator. Our framework
also leverages the strong exploratory capabilities of reinforcement
learning~(RL) to better explore the vast search space of formulaic alphas. The
contribution to the combination models' performance is assigned to be the
return used in the RL process, driving the alpha generator to find better
alphas that improve upon the current set. Experimental evaluations on
real-world stock market data demonstrate both the effectiveness and the
efficiency of our framework for stock trend forecasting. The investment
simulation results show that our framework is able to achieve higher returns
compared to previous approaches.Comment: Accepted by KDD '23, ADS trac
Optimisation- based time slot assignment and synchronisation for TDMA MAC in industrial wireless sensor network
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166209/1/cmu2bf02232.pd
ELODI: Ensemble Logit Difference Inhibition for Positive-Congruent Training
Negative flips are errors introduced in a classification system when a legacy
model is replaced with a new one. Existing methods to reduce the negative flip
rate (NFR) either do so at the expense of overall accuracy using model
distillation, or use ensembles, which multiply inference cost prohibitively. We
present a method to train a classification system that achieves paragon
performance in both error rate and NFR, at the inference cost of a single
model. Our method introduces a generalized distillation objective, Logit
Difference Inhibition (LDI), that penalizes changes in the logits between the
new and old model, without forcing them to coincide as in ordinary
distillation. LDI affords the model flexibility to reduce error rate along with
NFR. The method uses a homogeneous ensemble as the reference model for LDI,
hence the name Ensemble LDI, or ELODI. The reference model can then be
substituted with a single model at inference time. The method leverages the
observation that negative flips are typically not close to the decision
boundary, but often exhibit large deviations in the distance among their
logits, which are reduced by ELODI.Comment: Tech repor
CharacterChat: Learning towards Conversational AI with Personalized Social Support
In our modern, fast-paced, and interconnected world, the importance of mental
well-being has grown into a matter of great urgency. However, traditional
methods such as Emotional Support Conversations (ESC) face challenges in
effectively addressing a diverse range of individual personalities. In
response, we introduce the Social Support Conversation (S2Conv) framework. It
comprises a series of support agents and the interpersonal matching mechanism,
linking individuals with persona-compatible virtual supporters. Utilizing
persona decomposition based on the MBTI (Myers-Briggs Type Indicator), we have
created the MBTI-1024 Bank, a group that of virtual characters with distinct
profiles. Through improved role-playing prompts with behavior preset and
dynamic memory, we facilitate the development of the MBTI-S2Conv dataset, which
contains conversations between the characters in the MBTI-1024 Bank. Building
upon these foundations, we present CharacterChat, a comprehensive S2Conv
system, which includes a conversational model driven by personas and memories,
along with an interpersonal matching plugin model that dispatches the optimal
supporters from the MBTI-1024 Bank for individuals with specific personas.
Empirical results indicate the remarkable efficacy of CharacterChat in
providing personalized social support and highlight the substantial advantages
derived from interpersonal matching. The source code is available in
\url{https://github.com/morecry/CharacterChat}.Comment: 10 pages, 6 figures, 5 table
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