Dear Colleagues,

The emerging field of multimodal machine learning has experienced much progress in the past few years; however, several core challenges remain. These challenges are mainly around learning how to represent and summarise multimodal data (representation); translating (mapping) data from one modality to another (translation); identifying direct relations between elements from different modalities (alignment); joining or fusing information from two or more modalities to perform a prediction task (fusion); and transferring knowledge between modalities, their representations, and predictive models (co-learning).

Within the field of information retrieval, the large and continually growing volume of data has given rise to the need for retrieval solutions that can deal with the search process of using one modality as a query to retrieve related information in another modality, known as cross-modal retrieval. In recent years, cross-modal retrieval methods have attracted considerable attention due to the learning capabilities of deep learning methods; however, most of these methods assume that data examples in different modalities are fully paired, when in reality, these data are not often paired.

Furthermore, the continually growing volume of data has given rise to the additional challenge of developing lifelong learning models than can continue to efficiently learn new volumes of data. Lifelong learning remains a challenge for machine learning models and most research on the topic focuses on classification tasks. There is a need to focus on lifelong learning for information retrieval and to propose methods for dealing with the continuous growth of information that can lead to catastrophic forgetting or interference. This limitation represents a major drawback for models that typically learn representations from batches of training data, when in reality, information becomes incrementally available over time. The challenge of lifelong learning increases when dealing with cross-modal learning.

We request contributions that present techniques that will contribute to addressing the multimodal machine learning challenges, and we strongly encourage contributions that propose advances in the field of continual lifelong learning for multimodal machine learning applications. 

Dr. Georgina Cosma
Guest Editor

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• neural information retrieval
• multi-modal and cross-modal information retrieval
• relevance feedback and query expansion in multimodal retrieval
• sensitivity analysis of images or multi-modal data
• visual semantic embedding for information retrieval and other tasks
• continual lifelong learning for information retrieval
• temporal modelling of multi-modal data