MP: A Protocol for Efficient Exchange of Mathematical Expressions 

    The Multi Protocol (MP) is designed for integrating symbolic,
    numeric, graphics, document processing, and other tools for
    scientific computation, into a single distributed problem-solving
    environment.  MP is layered, reflecting the logically distinct 
    aspects of tool integration.  Data representation issues are 
    addressed by specifying a set of basic data types and a mechanism 
    for constructing non-basic types.  MP passes all data in the form 
    of annotated parse trees.  The parse tree provides a simple, 
    flexible and tool-independent way to represent and exchange data, 
    and annotations provide a powerful and generic expressive facility 
    for transmitting additional information.  MP also provides efficient 
    encodings for numeric data and includes different types of 
    optimizations to reduce the cost of exchanging data.  The 
    optimizations are important when transmitting large expressions 
    typically encountered in symbolic and numeric computation.  MP is 
    extensible. Users can define additional sets of operators and 
    annotations as well as tailor the generic optimization mechanisms 
    to efficiently encode their own data structures.  A clear distinction 
    between MP-defined and user-defined definitions is enforced.