Energy-Based Models

Energy-Based Models assign a numerical score, called energy, to each candidate output. An output might be an image, a scene interpretation, a reasoning solution, or a robot trajectory. Lower energy indicates a better fit to the input or constraints. We can search the learned landscape for one low-energy solution or sample from it to obtain several plausible solutions. We can also compose models by adding their energies and searching for outputs with low total energy.

Our research develops energy landscapes as reusable representations. After training, we combine and search these landscapes to solve new generation, reasoning, and planning problems.

Browse publications ↓ Implicit generation with EBMs (2019) ↗

Representation and inference

An EBM separates the representation of a distribution from the procedure used to generate outputs. Here, x is the input, y is a candidate output, and θ denotes the learned parameters. Training updates θ. At inference time, θ remains fixed while we optimize or sample over y. Because the energy function remains available during inference, we can add new energy terms representing additional goals or constraints. If the EBM is trained as a joint energy over several variables, we can also fix any observed variables and infer the others.

Representation

pθ(y | x) = exp(−Eθ(x, y)) / Zθ(x)

The energy defines a distribution in which lower-energy outputs have higher probability density (or probability for discrete outputs).

Learning the energy. One common approach is maximum-likelihood training. It lowers the energy of observed input-output pairs and raises the energy of alternatives sampled from the current model. Repeating this process shapes the model distribution toward the training data.

The partition function. Zθ(x) is the partition function: the sum or integral of exp(−Eθ(x, y)) over every possible output y. Dividing by Z makes the distribution sum or integrate to one. In high-dimensional output spaces, computing Z exactly is generally intractable. Training therefore often uses samples or objectives that avoid evaluating Z directly.

One solution (MAP)

ŷ = arg miny Eθ(x, y)

Search for the lowest-energy output. In probabilistic terms, this is the maximum a posteriori (MAP) solution.

Multiple solutions (Langevin)

yt+1 = yt − η∇yEθ(x, yt) + √(2η) εt

Langevin dynamics is a gradient-based Markov chain Monte Carlo (MCMC) procedure: it repeatedly moves a candidate toward lower energy while adding noise. Different initializations and noise can produce different plausible outputs.

Both procedures use the same learned energy function. MAP seeks a most likely output, while Langevin dynamics approximately samples the distribution. In the Langevin equation, η is the step size and εt is standard Gaussian noise. This update assumes that y is continuous and the energy is differentiable with respect to y. Discrete outputs require a different search or relaxation procedure.

Figure 1. Gradient descent and Langevin sampling

We can compare these procedures on an energy over a single continuous output z. Starting from the same point in the right valley, gradient descent searches for one low-energy output, while Langevin dynamics explores the distribution defined by the energy.

Energy and candidate positions
-1.00.62.23.8-2-1012E(z)zglobal min.
Gradient descentLangevin chainsShared start
Target density and sampled positions
0.00.51.11.6-2-1012Densityz
Target densityCurrent chain positions
3,000 steps
Completed seeded run

Descent is at z = 1.06, near a global minimum. 75% of the chains are on the right, compared with 74% of the target probability.

In the default run, gradient descent (magenta) reaches the global minimum on the right, giving the most likely output. Langevin chains (teal) occupy both valleys, with more chains in the lower-energy valley. Their histogram approximates the normalized target density (black), illustrating how sampling represents uncertainty across plausible outputs.
Explore parameters and numerical details

Increasing b makes barrier crossing harder. Negative a favors the right basin; positive a favors the left. T changes the target density and the amount of Langevin noise. Changing a parameter resets the run; press “Run comparison” to see the result.

E(z) = b(z² − 1)² + az,   pT(z) = exp(−E(z)/T) / ZT

Both procedures start at z₀ = 1.6. We show 128 chains after 3,000 unadjusted Langevin updates with η = 0.003 and independent standard Gaussian noise: zk+1 = zk − ηE′(zk) + √(2ηT) εk. The initial view is the result of this seeded simulation; replay follows the same updates. The default initialization lets gradient descent reach the global minimum, but this is not guaranteed in general. For example, changing the tilt to favor the left valley can leave descent in the right local minimum.

All calculations use [−2.4, 2.4], with reflecting boundaries for sampling and projection for descent. A 601-point grid supplies the target normalization and global-minimum estimate. The histogram uses 24 bins and a vertical scale fixed across the displayed replay frames. Energy values above the display range are clipped. Finite-time mixing, Monte Carlo variation, and discretization bias can prevent agreement with the target; Langevin is not guaranteed to cross a barrier in a given run.

What is an Energy-Based Model?

An EBM assigns an energy Eθ(x, y) to every candidate output y given an input x. This energy defines the conditional probability distribution pθ(y | x), where the partition function Zθ(x) normalizes the probabilities over all possible outputs.

A scalar energy function defines an unnormalized density: relative likelihoods before normalization. Autoregressive models represent an output as a fixed sequence of predictions, while diffusion models learn a multi-step denoising process. An EBM does not require either structure. These categories can overlap: a diffusion model can be parameterized so that its denoising direction is derived from an energy at each noise level. This flexibility comes with computational costs: the partition function is generally intractable, and both training and inference can be difficult.

Many conventional predictors produce an answer through a fixed forward computation. An EBM retains an energy function that we can evaluate, optimize, or use for sampling, including after adding new requirements.

Each energy function can represent one component of a problem, such as dynamics, a goal, or a constraint. Adding these energies lets us search for outputs that satisfy the components together. Their relative weights determine how the combined model balances competing requirements. A robot planner, for example, can combine a learned dynamics energy with an energy for a new goal, then find a trajectory that follows the dynamics and reaches the goal. Because the component models remain separate, we can change the goal or add another constraint without retraining the full system.

My PhD thesis, Learning Generalizable Systems by Learning Composable Energy Landscapes, develops this approach: learning reusable energy landscapes from data, then composing and optimizing them at inference time to solve tasks not represented directly in the training set.

Flexible representationA single energy can represent a distribution without a prescribed variable ordering, factorization, or noising process.
Multiple inference proceduresThe same landscape supports optimization, sampling, and decision-making under a utility or constraint.
CompositionAdd compatible, appropriately weighted energy functions and search for an output with low total energy, such as a trajectory that follows learned dynamics and reaches a new goal.

Why Energy-Based Models?

An EBM separates the representation of a problem from the procedure used to solve it. The same learned model can therefore support different tasks and inference procedures.

Represent complex distributions directly

An energy function scores a complete configuration. Unlike an autoregressive model, it does not need to generate the variables one at a time in a fixed order. Unlike a diffusion model, it does not require a prescribed process that adds noise and then learns to reverse it.

Compose different kinds of knowledge

When concepts, relations, dynamics, goals, and constraints are encoded as compatible energies over shared variables, their weighted sum creates a new landscape that balances these components. We can therefore form a new inference problem without retraining the models jointly.

Reuse structure across scale

Each model can score a small part of a problem, while the summed energy defines the full structured problem. A relation learned between two objects can be reused in a scene with many objects, and a local dynamics model can be applied repeatedly across a longer plan. The same models can therefore support different numbers of objects, longer horizons, or new task layouts.

Flexible inference-time computation

An energy function does not fix a single way of producing an answer. We can minimize it for one solution, sample from it for several possibilities, or combine it with a utility or constraint to make a decision. Harder problems can use more optimization steps or maintain more candidate solutions at inference time.

Co-design the landscape and the solver

A model is useful only if inference can reach its low-energy regions. We can train the landscape with the chosen solver in mind, so that low-energy solutions are also accessible to optimization or sampling. Inference can begin on a smoother landscape and gradually sharpen it, or optimize several candidates in parallel.

A joint energy can condition in either direction

If one energy function scores x and y together, we can hold x fixed and infer y, or hold y fixed and infer x. This requires a joint model. The conditional formula above only models y given x. For example, the same relational model can generate a scene that satisfies several relations or infer the relations present in an observed scene, as in Learning to Compose Visual Relations.

Properties and connections

EBMs connect probabilistic modeling with optimization, sampling, and inference-time computation.

EBMs as generative models

An EBM specifies relative likelihoods through exp(−E), so we can compare candidates without evaluating the partition function. Finding a most likely output requires minimizing the energy over the output space. MCMC methods such as Langevin dynamics generate samples by repeatedly moving a candidate toward lower energy while adding noise.

Relationship to diffusion models

Diffusion models learn how to move a noisy sample toward more likely data at many noise levels. In an energy-based parameterization, the score at each noise level is the negative gradient of a scalar energy function. This connection lets us use energy-based sampling and composition within diffusion models. In our work, we study energy-based diffusion samplers, as well as how to blend diffusion objectives to build equilibrium energy landscapes.

Composition by adding energies

To compose EBMs, we add their energies and run inference in the resulting landscape. When component scales are compatible or explicitly weighted, low-total-energy candidates tend to score well across them. Probabilistically, adding energies multiplies the models’ relative likelihoods. Composition can fail if one model’s scores dominate or the sampler cannot reach a region that satisfies the components together.

Inference for reasoning and planning

An energy function can score candidate answers or trajectories without generating them in one pass. Inference searches across candidates and refines the low-energy ones. Harder problems can use more optimization steps or maintain several candidates in parallel, while new goals or constraints can enter as additional energy terms.

Figure 2. Composing a model with a goal energy

For example, suppose z is a gripper’s final position and the original model assigns low energy to positions near −1 and +1. A new goal can enter as a quadratic energy that penalizes distance from the desired position.

Adding a goal energy
03710-2-1012Energyzgoal
Original energy EAAdded goal energy λEBSum EA + λEB
Original and composed densities
0.00.71.42.1-2-1012Densityzgoal
Original densityComposed density

The original model assigns 50% probability to each side. With the right goal, 98% of the composed probability lies on the requested side; the original energy stays fixed.

The teal curve shows the added goal energy. Its sum with the original energy (magenta) gives the composed energy (black), whose density is shown on the right. Changing the goal shifts probability toward the desired position without retraining the original model. “No added goal” recovers the original distribution. This example expresses a soft preference over final positions and does not model dynamics or collision avoidance.
E = EA + λEB   ⟹   p(z) ∝ pA(z) pB(z)λ
Explore the goal and its weight

Adding energies multiplies their unnormalized densities, favoring outputs with low energy under both components. Increasing λ gives the goal more influence. Move the goal between the original modes to see how the composed model trades off its original preferences against the added goal.

At T = 1, EA(z) = 1.3(z² − 1)² and EB(z) = (z − g)² / (2 × 0.55²). The teal curve is the weighted term λEB that enters the sum. Both densities are normalized on [−2.4, 2.4]. The energy scale is fixed, with high values clipped. Composition requires compatible variables and meaningful relative energy scales. A soft goal does not guarantee satisfaction of a constraint.

Conditions for compositional generalization

Composition is most reliable when each model encounters local configurations covered during training and the models agree on the meaning and scale of their shared variables. For example, a dynamics model is more likely to remain accurate under a new goal if the resulting trajectory stays within familiar states. The global combination may be new even when each local configuration is familiar.

Computational and compositional limitations

These advantages depend on effective inference. Computing normalized probabilities requires evaluating the partition function, which is often intractable. Optimization and MCMC can also be slow or sensitive to initialization. When several energies are composed, one component may dominate, the combined landscape may contain new local minima, or the component models may be unreliable in different regions.

Historical context

Energy-Based Models borrow a simple idea from statistical physics: represent each configuration with a scalar energy, so that lower-energy configurations are more probable or more compatible. Hopfield networks used an energy landscape to describe attractor dynamics and associative memory. Boltzmann machines made these dynamics stochastic and showed how an energy function could be learned from data.

Later work developed more practical and general ways to learn energy functions. Hinton’s Products of Experts introduced contrastive divergence for training product-form latent-variable models. Score matching and noise-contrastive estimation provided other ways to learn unnormalized densities without directly evaluating the partition function. LeCun et al. unified these ideas as energy-based prediction: score candidate outputs, then optimize or search for a low-energy one. This work emphasized prediction and structured outputs, while later neural EBM research placed greater emphasis on MCMC sampling for generation.

In our 2019 paper, we showed that MCMC-based training of continuous neural EBMs could scale to high-dimensional images and robotic trajectories, using Langevin dynamics for both learning and generation. We also studied compositional generation, reconstruction, robustness, continual learning, and trajectory prediction. Our subsequent work develops energy functions as reusable representations that can be optimized, conditioned, and composed at inference time.

Publications

Equilibrium Matching generative samples

Equilibrium Matching: Generative Modeling with Implicit Energy-Based Models

Runqian Wang, Yilun Du
arXiv 2025
[Project] [Paper] [Code]

We introduce Equilibrium Matching (EqM), a generative modeling framework built from an equilibrium dynamics perspective. EqM discards the non-equilibrium, time-conditional dynamics in traditional diffusion and flow-based generative models and instead learns the equilibrium gradient of an implicit energy landscape. At inference time, EqM initializes candidates from noise and generates samples by optimizing the learned landscape with gradient descent. Different initializations can produce different outputs, and the optimization can use adjustable step sizes, adaptive optimizers, and adaptive compute. EqM surpasses the generation performance of diffusion/flow models empirically, achieving an FID of 1.90 on ImageNet 256×256. EqM is also theoretically justified to learn and sample from the data manifold. Beyond generation, EqM is a flexible framework that naturally handles tasks including partially noised image denoising, OOD detection, and image composition. By replacing time-conditional velocities with an equilibrium landscape, EqM connects flow and Energy-Based Models through optimization-based inference.


Compositional energy minimization for reasoning

Generalizable Reasoning through Compositional Energy Minimization

Alexandru Oarga, Yilun Du
NeurIPS 2025
[Project] [Paper] [Code]

Generalization is a key challenge in reasoning tasks, where models are expected to solve problems more complex than those encountered during training. Existing approaches typically train reasoning models in an end-to-end fashion, directly mapping input instances to solutions. While this allows models to learn useful heuristics from data, it often results in limited generalization beyond the training distribution. We approach reasoning generalization by learning energy landscapes over the solution spaces of smaller, more tractable subproblems. At test time, we construct a global energy landscape for a given problem by combining the energy functions of multiple subproblems. This composition lets us add constraints during inference and construct energy landscapes for increasingly difficult problems. To improve sample quality from the composed energy landscape, we introduce Parallel Energy Minimization (PEM). We evaluate our approach on a wide set of reasoning problems. Our method outperforms existing state-of-the-art methods, demonstrating its ability to generalize to larger and more complex problems.


Energy-Based Transformer architecture and inference

Inference-time computation techniques, analogous to human System 2 Thinking, have recently become popular for improving model performance. However, most existing approaches suffer from several limitations: they are modality-specific (e.g., working only in text), problem-specific (e.g., verifiable domains like math and coding), or require additional supervision/training on top of unsupervised pretraining (e.g., verifiers or verifiable rewards). We ask whether these System 2 Thinking approaches can generalize across tasks and emerge solely from unsupervised learning. We find that they can, by learning to verify compatibility between inputs and candidate predictions, then framing prediction as optimization with respect to this verifier. Specifically, we train Energy-Based Transformers (EBTs)—a new class of Energy-Based Models (EBMs)—to assign an energy to every input and candidate prediction pair, with lower energy indicating greater compatibility, and obtain predictions through gradient-based energy minimization. This formulation enables System 2 Thinking to emerge from unsupervised learning, making it modality and problem agnostic. Across both discrete (text) and continuous (visual) modalities, we find EBTs scale faster than the dominant Transformer++ approach during training, achieving up to a 35% higher scaling rate with respect to data, batch size, parameters, FLOPs, and depth. During inference, EBTs improve performance with System 2 Thinking (i.e., extra computation) by 29% more than the Transformer++ on language tasks, and EBTs outperform Diffusion Transformers on image denoising while using fewer forward passes. Further, we find that System 2 Thinking with EBTs yields larger performance improvements on data that is farther out-of-distribution, and that EBTs achieve better results than existing models on most downstream tasks given the same or worse pretraining performance, suggesting that EBTs generalize better than existing approaches. Consequently, EBTs are a promising new paradigm for scaling both the learning and thinking capabilities of models.


Compositional inverse generative modeling

Compositional Scene Understanding through Inverse Generative Modeling

Yanbo Wang, Justin Dauwels, Yilun Du
ICML 2025
[Project] [Paper] [Code]

We explore how generative models can be used not only to synthesize visual content but also to understand the properties of a scene given a natural image. We formulate scene understanding as an inverse generative modeling problem, where we infer the conditioning parameters of a visual generative model that best fit a given natural image. To enable this procedure to infer scene structure from images substantially different from those seen during training, we further propose to build this visual generative model compositionally from smaller models over pieces of a scene. This procedure infers the objects in a scene and generalizes robustly to test scenes with more objects and new shapes. It also infers global scene factors and generalizes robustly to new scenes. Finally, we illustrate how this approach can be directly applied to existing pretrained text-to-image generative models for zero-shot multi-object perception.


PhD thesis on composable energy landscapes

Learning Generalizable Systems by Learning Composable Energy Landscapes

Yilun Du
MIT PhD Thesis 2024
[Thesis] [Defense]

This thesis develops energy landscapes as a representation for prediction problems. Test-time search can incorporate new constraints, while compositions of learned landscapes construct models for unseen combinations of factors. It develops methods for probabilistic, deterministic, and annealed energies; an algebra for logical, probabilistic, graphical-model, and hierarchical composition; and applications across vision, robotics, foundation models, and scientific design.


Iterative reasoning through energy diffusion

Learning Iterative Reasoning through Energy Diffusion

Yilun Du*, Jiayuan Mao*, Joshua Tenenbaum
ICML 2024
[Project] [Paper] [Code]

We introduce iterative reasoning through energy diffusion (IRED), a framework that formulates reasoning and decision-making tasks as energy-based optimization problems. IRED learns energy functions to represent the constraints between input conditions and desired outputs. After training, IRED adapts the number of optimization steps during inference based on problem difficulty, enabling it to solve problems outside its training distribution, such as more complex Sudoku puzzles, matrix completion with large value magnitudes, and pathfinding in larger graphs. Two techniques are central to the method: learning a sequence of annealed energy landscapes for easier inference and a combination of score function and energy landscape supervision for faster and more stable training. Our experiments show that IRED outperforms existing methods in continuous-space reasoning, discrete-space reasoning, and planning tasks, particularly in more challenging scenarios.


Compositional image decomposition with diffusion models

Compositional Image Decomposition with Diffusion Models

Jocelin Su*, Nan Liu*, Yanbo Wang*, Joshua B. Tenenbaum, Yilun Du
ICML 2024
[Project] [Paper] [Code]

Given an image of a natural scene, we are able to quickly decompose it into a set of components such as objects, lighting, shadows, and foreground. We can then envision a scene where we combine certain components with those from other images, for instance a set of objects from our bedroom and animals from a zoo under the lighting conditions of a forest, even if we have never encountered such a scene before. In this paper, we present a method to decompose an image into such compositional components. Our approach, Decomp Diffusion, is an unsupervised method which, when given a single image, infers a set of different components in the image, each represented by a diffusion model. We demonstrate how components can capture different factors of the scene, ranging from global scene descriptors like shadows or facial expression to local scene descriptors like constituent objects. We further illustrate how inferred factors can be flexibly composed, even with factors inferred from other models, to generate a variety of scenes substantially different from those seen during training.


Potential-based diffusion motion planning

Effective motion planning in high-dimensional spaces is a long-standing problem in robotics. Potential-based planners are naturally compositional: different motion constraints can be combined by adding their potentials. However, finding a path requires global optimization over the configuration-space landscape and is often vulnerable to local minima. We learn an easily optimized potential over motion trajectories. The resulting planner outperforms classical and learned alternatives, avoids many local-minimum failures, and composes across a wide range of motion constraints.


Compositional generative modeling framework

Compositional Generative Modeling: A Single Model is Not All You Need

Yilun Du, Leslie Kaelbling
ICML 2024
[Paper]

Large monolithic generative models trained on massive amounts of data have become an increasingly dominant approach in AI research. In this paper, we argue that we should instead construct large generative systems by composing smaller generative models. This compositional approach learns distributions more efficiently from data and generalizes to parts of the distribution unseen during training. It also lets us construct new generative models for tasks completely unseen during training. Finally, we show that in many cases, we can discover separate compositional components from data.


Unsupervised Compositional Concepts Discovery with Text-to-Image Generative Models

Nan Liu*, Yilun Du*, Shuang Li*, Joshua B. Tenenbaum, Antonio Torralba
ICCV 2023
[Project] [Paper] [Code]

Text-to-image generative models have enabled high-resolution image synthesis across different domains, but require users to specify the content they wish to generate. We consider the inverse problem: discovering the generative concepts that represent each image in a collection. We present an unsupervised approach to discover generative concepts from a collection of images, disentangling different art styles in paintings, objects, and lighting from kitchen scenes, and discovering image classes given ImageNet images. We show how such generative concepts can accurately represent the content of images, be recombined and composed to generate new artistic and hybrid images, and be further used as a representation for downstream classification tasks.



Systems consisting of interacting agents are prevalent in the world, ranging from dynamical systems in physics to complex biological networks. To build systems which can interact robustly in the real world, it is thus important to be able to infer the precise interactions governing such systems. Existing approaches typically discover such interactions by explicitly modeling the feed-forward dynamics of the trajectories. In this work, we propose Neural Interaction Inference with Potentials (NIIP) as an alternative approach to discover such interactions that enables greater flexibility in trajectory modeling: it discovers a set of relational potentials, represented as energy functions, which when minimized reconstruct the original trajectory. NIIP assigns low energy to the subset of trajectories which respect the relational constraints observed. These representations give NIIP several capabilities at test time. First, it allows trajectory manipulation, such as interchanging interaction types across separately trained models, as well as trajectory forecasting. Additionally, it allows adding external hand-crafted potentials at test-time. Finally, NIIP enables the detection of out-of-distribution samples and anomalies without explicit training.



Since their introduction, diffusion models have quickly become the prevailing approach to generative modeling in many domains. They can be interpreted as learning the gradients of a time-varying sequence of log-probability density functions. This interpretation has motivated classifier-based and classifier-free guidance as methods for post-hoc control of diffusion models. In this work, we build upon these ideas using the score-based interpretation of diffusion models, and explore alternative ways to condition, modify, and reuse diffusion models for tasks involving compositional generation and guidance. In particular, we investigate why certain types of composition fail using current techniques and present a number of solutions. We conclude that the sampler (not the model) is responsible for this failure and propose new samplers, inspired by MCMC, which enable successful compositional generation. Further, we propose an energy-based parameterization of diffusion models which enables the use of new compositional operators and more sophisticated, Metropolis-corrected samplers. We find that these samplers lead to notable improvements in compositional generation across a wide set of problems such as classifier-guided ImageNet modeling and compositional text-to-image generation.


Composing Ensembles of Pre-trained Models via Iterative Consensus

Shuang Li*, Yilun Du*, Joshua B. Tenenbaum, Antonio Torralba, Igor Mordatch
(*equal contribution. Shuang Li did experiments on image generation, video question answering, and mathematical reasoning. Yilun Du did all the experiments on robot manipulation.)
ICLR 2023
[Project] [Paper]

Large pre-trained models exhibit distinct and complementary capabilities dependent on the data they are trained on. Language models such as GPT-3 are capable of textual reasoning but cannot understand visual information, while vision models such as DALL-E can generate photorealistic photos but fail to understand complex language descriptions. In this work, we propose a unified framework for composing ensembles of different pre-trained models -- combining the strengths of each individual model to solve various multimodal problems in a zero-shot manner. We use pre-trained models as "generators" or "scorers" and compose them via closed-loop iterative consensus optimization. The generator constructs proposals and the scorers iteratively provide feedback to refine the generated result. Such closed-loop communication enables models to correct errors caused by other models, significantly boosting performance on downstream tasks, e.g. improving accuracy on grade school math problems by 7.5%, without requiring any model finetuning. We demonstrate that consensus achieved by an ensemble of scorers outperforms the feedback of a single scorer, by combining the strengths of each expert model. Results show that the proposed method can be used as a general-purpose framework for a wide range of zero-shot multimodal tasks, such as image generation, video question answering, mathematical reasoning, and robotic manipulation.


Compositional Visual Generation with Composable Diffusion Models

Nan Liu*, Shuang Li*, Yilun Du*, Antonio Torralba, and Joshua B. Tenenbaum
(*equal contribution)
ECCV 2022
[Project] [Paper] [Code] [Colab] [HuggingFace Demo]
Press coverage: MIT News, MIT CSAIL News

Large text-guided diffusion models, such as DALLE-2, are able to generate photorealistic images given natural language descriptions. While such models are highly flexible, they struggle to understand the composition of certain concepts, such as confusing the attributes of different objects or relations between objects. In this paper, we propose an alternative structured approach for compositional generation using diffusion models. An image is generated by composing a set of diffusion models, with each of them modeling a certain component of the image. To do this, we interpret diffusion models as Energy-Based Models in which the data distributions defined by the energy functions may be explicitly combined. The proposed method can generate scenes at test time that are substantially more complex than those seen in training, composing sentence descriptions, object relations, human facial attributes, and even generalizing to new combinations that are rarely seen in the real world. We further illustrate how our approach may be used to compose pre-trained text-guided diffusion models and generate photorealistic images containing all the details described in the input descriptions, including the binding of certain object attributes that have proved difficult for DALLE-2. These results point to the effectiveness of the proposed method in promoting structured generalization for visual generation.


Energy-Based Models for continual learning

We motivate Energy-Based Models (EBMs) as a promising model class for continual learning. Instead of relying on external memory, growing models, or regularization, EBMs change the training objective to reduce interference with previously learned information. Our approach is simple, efficient, and outperforms baselines by a large margin on several benchmarks. Its contrastive-divergence objective can also be combined with other continual-learning methods, producing substantial improvements.


Learning Iterative Reasoning through Energy Minimization

Yilun Du, Shuang Li, Joshua B. Tenenbaum, and Igor Mordatch
ICML 2022
[Project] [Paper] [Code]

Deep learning has excelled on complex pattern recognition tasks such as image classification and object recognition. However, it struggles with tasks requiring nontrivial reasoning, such as algorithmic computation. Humans solve such tasks through iterative reasoning, spending more time thinking about harder tasks. Most existing neural networks, however, exhibit a fixed computational budget controlled by the neural network architecture, preventing additional computational processing on harder tasks. In this work, we present a new framework for iterative reasoning with neural networks. We train a neural network to parameterize an energy landscape over all outputs, and implement each step of the iterative reasoning as an energy minimization step to find a minimal energy solution. This formulation lets us allocate more computation to harder problems with more complex energy landscapes by using a more complex optimization procedure. Our experiments show that this approach solves algorithmic reasoning tasks more accurately and generalizes better in both graph and continuous domains. Finally, we illustrate that our approach can recursively solve algorithmic problems requiring nested reasoning.


Unsupervised compositional energy concepts

Unsupervised Learning of Compositional Energy Concepts

Yilun Du, Shuang Li, Yash Sharma, Joshua B. Tenenbaum, and Igor Mordatch
NeurIPS 2021
[Project] [Paper] [Code]

We introduce an approach to decompose images, in an unsupervised manner, into separate component energy functions. These energy functions can represent both global factors of variation, such as facial expression and hair color, and local factors of variation, such as the objects in a scene. Decomposed energy functions generalize well and may be recombined with energy functions discovered by training a separate instance of the approach on another dataset, enabling the recombination of objects and lighting conditions across datasets.


Learning to Compose Visual Relations

Nan Liu*, Shuang Li*, Yilun Du*, Joshua B. Tenenbaum, and Antonio Torralba
(*equal contribution)
NeurIPS 2021, Spotlight
NeurIPS Workshop on Controllable Generative Modeling 2021, Outstanding Paper Award
Press coverage: MIT News, MIT CSAIL News
[Project] [Paper] [Code]

The visual world around us can be described as a structured set of objects and their associated relations. In this work, we propose to represent each relation as an unnormalized density (an energy-based model), enabling us to compose separate relations in a factorized manner. We show that such a factorized decomposition allows the model to both generate and edit scenes that have multiple sets of relations more faithfully. We further show that decomposition enables our model to effectively understand the underlying relational scene structure.


Improved contrastive divergence training for Energy-Based Models

Improved Contrastive Divergence Training of Energy Based Models

Yilun Du, Shuang Li, Joshua B. Tenenbaum, and Igor Mordatch
ICML 2021
ICLR EBM Workshop 2021, Oral
[Project] [Paper] [Code]

We present tools to improve contrastive divergence training of EBMs. First, we identify a neglected term in the objective and present a loss function to mitigate it. We use data augmentation to improve MCMC mixing during training and a multiscale architecture to improve generative performance. These techniques improve both generation and out-of-distribution detection.


Compositional visual generation with Energy-Based Models

Compositional Visual Generation and Inference with Energy Based Models

Yilun Du, Shuang Li, and Igor Mordatch
NeurIPS 2020, Spotlight
[Project] [Paper] [Code]

A vital aspect of human intelligence is the ability to compose increasingly complex concepts out of simpler ideas, enabling both rapid learning and adaptation of knowledge. In this paper we show that Energy-Based Models can exhibit this ability by directly combining probability distributions. Samples from the combined distribution correspond to compositions of concepts. For example, given one distribution for smiling face images, and another for male faces, we can combine them to generate smiling male faces. This allows us to generate natural images that simultaneously satisfy conjunctions, disjunctions, and negations of concepts. We evaluate compositional generation abilities of our model on the CelebA dataset of natural faces and synthetic 3D scene images. We showcase the breadth of unique capabilities of our model, such as the ability to continually learn and incorporate new concepts, or infer compositions of concept properties underlying an image.


Atomic-level protein conformation energy model

Energy-Based Models for Atomic-Resolution Protein Conformations

Yilun Du, Joshua Meier, Jerry Ma, Rob Fergus, and Alexander Rives
ICLR 2020, Spotlight
[Paper] [Code]

We propose an energy-based model (EBM) of protein conformations that operates at atomic scale. The model is trained solely on crystallized protein data. By contrast, existing approaches for scoring conformations use energy functions that incorporate knowledge of physical principles and features that are the complex product of several decades of research and tuning. To evaluate the model, we benchmark on the rotamer recovery task, the problem of predicting the conformation of a side chain from its context within a protein structure, which has been used to evaluate energy functions for protein design. The model achieves performance close to that of the Rosetta energy function, a state-of-the-art method widely used in protein structure prediction and design. An investigation of the model’s outputs and hidden representations finds that it captures physicochemical properties relevant to protein energy.


Model-based planning with Energy-Based Models

Model Based Planning with Energy Based Models

Yilun Du, Toru Lin, and Igor Mordatch
CORL 2019
ICML MBRL Workshop 2019, Oral
[Paper] [Code]

Model-based planning holds great promise for improving both sample efficiency and generalization in reinforcement learning (RL). We show that Energy-Based Models (EBMs) are a promising class of models to use for model-based planning. EBMs naturally support inference of intermediate states given start and goal state distributions. We provide an online algorithm to train EBMs while interacting with the environment, and show that EBMs allow for significantly better online learning than corresponding feed-forward networks. We further show that EBMs support maximum entropy state inference and are able to generate diverse state space plans. We show that inference purely in state space, without planning actions, allows for better generalization to previously unseen obstacles in the environment and prevents the planner from exploiting the dynamics model by applying uncharacteristic action sequences.


Implicit Generation and Generalization in Energy-Based Models

Yilun Du and Igor Mordatch
NeurIPS 2019, Spotlight
[OpenAI Blog] [Paper] [Code]

Energy-Based Models (EBMs) are an appealing class of models due to their generality and simplicity in likelihood modeling. However, EBMs have traditionally been difficult to train. We present techniques to scale MCMC-based EBM training on continuous neural networks in high-dimensional domains such as ImageNet and robotic hand trajectories. We highlight unique capabilities of implicit generation. Finally, we illustrate how EBMs are useful across a wide variety of tasks, including out-of-distribution classification, adversarially robust classification, online continual learning, and compositionality.


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