______________ is a deep learning framework developed by Microsoft, known for its efficiency and scalability, especially on large-scale distributed systems.

The answer to the question is Microsoft Cognitive Toolkit (CNTK).

CNTK is a powerful and versatile deep learning framework designed for performance and scalability, particularly suited for training deep learning models on large datasets across multiple GPUs and distributed computing environments. It supports various neural network architectures including feedforward networks, convolutional networks, and recurrent networks. One of its key strengths is the ability to efficiently leverage modern computational resources, allowing researchers and developers to build sophisticated models that can scale as needed without sacrificing performance or speed.

Additionally, CNTK provides a flexible and intuitive programming interface, enabling users to define and train networks with ease. Its integration with popular Python libraries and support for different types of back-end computational resources make it a strong choice for deep learning applications in both academia and industry settings.