Improving Logical Consistency of Large Language Models via Neuro-Symbolic Integration
Conceptos Básicos
Logically consistent large language models can be achieved by fine-tuning them using a principled neuro-symbolic reasoning approach that encourages the model to satisfy a given set of logical constraints.
Resumen
The paper introduces a novel fine-tuning strategy called Logically-Consistent LLMs (LOCO-LMS) that aims to improve the factuality and logical consistency of large language models (LLMs).
The key insights are:
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Factuality and logical consistency are intimately related. Factuality can be viewed as a simple form of consistency where the model's probability of a true fact should be one minus the probability of its negation. More complex logical constraints, such as implication, negation, and their combinations, pose challenges for current LLMs.
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The authors propose to fine-tune LLMs using a principled neuro-symbolic reasoning approach based on the semantic loss, which encourages the model to satisfy a given set of logical constraints. This is done by translating the constraints into a compact and differentiable computational graph that can be efficiently optimized.
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Experiments on the BeliefBank dataset show that LOCO-LMS can achieve better logical self-consistency and factuality compared to methods using external reasoners, while being more sample-efficient, especially in low-data regimes.
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LOCO-LMS fine-tuned on different types of logical constraints (negation, implication, their combination) exhibit improved consistency on the corresponding constraints, without hurting the model's fluency.
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LOCO-LMS fine-tuned on the BeliefBank dataset can also transfer their improved logical consistency to the unseen EntailmentBank dataset, outperforming the baseline LLM.
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Logically Consistent Language Models via Neuro-Symbolic Integration
Estadísticas
The BeliefBank dataset contains 1,072 annotated facts about 7 entities and 12,636 facts about 85 entities, along with 2,224 valid abstract logical implications.
The EntailmentBank dataset contains 302 implication trees spanning 805 constraints, with an average of 6.57 statement nodes and 2.66 constraints per tree.
Citas
"Factuality and consistency are intimately related. Enforcing factuality alone generally boils down to fine-tuning an LLM on a large KB of atomic facts."
"When it comes to self-consistency w.r.t. more complex reasoning scenarios, e.g., ensuring that LLMs can perform modus ponens without contradicting themselves, one line of research focuses on employing external reasoning tools such as MAX-SAT solvers at inference time."
Consultas más profundas
How can LOCO-LMS be extended to handle more complex logical constraints beyond implications and negations, such as disjunctions, quantifiers, or even first-order logic?
To extend LOCO-LMS for handling more complex logical constraints, several strategies can be employed. First, the framework can be adapted to incorporate disjunctions by modifying the semantic loss (SL) objective to account for multiple truth assignments that satisfy disjunctive conditions. This would involve augmenting the weighted model counting (WMC) approach to include configurations where at least one of the conditions holds true, thus allowing the model to learn from a broader set of logical relationships.
For quantifiers, such as "for all" (universal quantification) and "there exists" (existential quantification), LOCO-LMS can be enhanced by integrating quantifier handling mechanisms. This could involve creating specialized training datasets that include quantified statements and developing a method to translate these into logical constraints that the model can process. By leveraging techniques from first-order logic, the model could be trained to recognize and apply quantifiers in reasoning tasks, thereby improving its ability to handle statements that require more nuanced logical interpretations.
Additionally, incorporating first-order logic would necessitate a more sophisticated representation of facts and relationships. This could be achieved by using predicate logic to express facts in a way that captures their relational structure, allowing LOCO-LMS to reason about entities and their properties more effectively. The integration of advanced neuro-symbolic techniques, such as differentiable programming and symbolic reasoning, could facilitate the learning of these complex logical structures, enabling the model to generalize better across various reasoning scenarios.
How can the sensitivity of LOCO-LMS to prompt formats be further reduced, to ensure more consistent behavior across different prompts?
To reduce the sensitivity of LOCO-LMS to prompt formats, a multi-faceted approach can be adopted. One effective strategy is to implement a diverse prompt engineering process during training. By exposing the model to a wide variety of prompt formats and structures, it can learn to generalize better and respond consistently regardless of the specific wording or structure of the prompt. This could involve generating synthetic prompts that vary in phrasing, length, and complexity, thereby enriching the training dataset.
Another approach is to employ meta-learning techniques, where the model learns to adapt its responses based on the context of the prompt. This could involve training a meta-learner that fine-tunes the LOCO-LMS on-the-fly based on the characteristics of the incoming prompt, allowing it to adjust its reasoning strategies dynamically. Additionally, incorporating attention mechanisms that focus on the semantic content of prompts rather than their syntactic structure could help the model prioritize meaning over form, leading to more consistent outputs.
Furthermore, implementing a feedback loop where the model's responses are evaluated and corrected based on a set of predefined criteria could enhance its robustness to prompt variations. By continuously refining its understanding of what constitutes a correct response, LOCO-LMS can become less reliant on specific prompt formats and more adept at delivering accurate answers across diverse scenarios.
Can the neuro-symbolic integration approach used in LOCO-LMS be applied to improve the logical consistency of other types of neural models, such as knowledge graphs or commonsense reasoning systems?
Yes, the neuro-symbolic integration approach utilized in LOCO-LMS can be effectively applied to enhance the logical consistency of other types of neural models, including knowledge graphs and commonsense reasoning systems. In knowledge graphs, the integration of neuro-symbolic methods can facilitate the encoding of logical relationships and constraints directly into the graph structure. By applying semantic loss and probabilistic reasoning techniques, knowledge graphs can be fine-tuned to ensure that the relationships they represent are logically consistent, thereby improving their reliability as sources of factual information.
For commonsense reasoning systems, the neuro-symbolic approach can be particularly beneficial in addressing the inherent complexities of human-like reasoning. By incorporating logical constraints and reasoning capabilities into these systems, they can better handle ambiguous or contradictory information. This could involve training the models to recognize and apply commonsense rules and logical principles, allowing them to make more coherent inferences based on the available data.
Moreover, the flexibility of the semantic loss framework allows it to be adapted to various reasoning tasks, making it suitable for a wide range of applications beyond language models. By leveraging the strengths of both neural and symbolic reasoning, these systems can achieve higher levels of consistency and accuracy in their outputs, ultimately leading to more trustworthy and effective AI solutions.