7. A method, comprising: initiating, by an expression converter, a multi-user interactive math computing session including at least one refreshable braille display device and at least one visual presentation device; receiving, by the expression converter, math input data representing a presentation markup representation of a mathematical expression during the multi-user interactive math computing session; converting, by the expression converter, the math input data representing the presentation markup representation of the mathematical expression to a mathematical markup language (MathML) representation of the mathematical expression, using a first set of data conversion rules for converting presentation markup of mathematical expressions to MathML; converting, by the expression converter, the MathML representation of the mathematical expression to a set of braille output math characters, using a second set of data conversion rules for converting MathML to braille math output, wherein the set of braille math output characters includes at least one braille mathematical symbol that does not correspond to any character in the received input data or in the MathML representation of the mathematical expression; transmitting, by the expression converter, the set of braille output characters to the at least one refreshable braille display device, wherein the converting and transmitting of the braille output math characters is performed in real-time in response to the receiving the math input data representing the presentation markup representation of the mathematical expression, receiving, by the expression convertor, a plurality of single-character revisions to the mathematical expression during the multi-user interactive math computing session, including at least a first single-character revision received as braille math input from the at least one refreshable braille display device, and a second single-character revision received as presentation markup math input from the at least one visual presentation device; and in response to each of the plurality of single-character revisions to the mathematical expression received during the multi-user interactive math computing session; (a) determining an input data type of the received single-character revision to the mathematical expression; (b) determining a set of conversion rules for converting the revised mathematical expression to MathML, based on the determined input data type; (c) converting the revised mathematical expression incorporating the single-character revision into revised MathML of the mathematical expression, using the determined set of conversion rules; (d) converting the revised MathML of the mathematical expression into one or more output math formats comprising at least one of braille math output or presentation markup math output; and (e) transmitting the revised mathematical expression, converted into the one or more output math formats to one or more output devices including at least one of the visual presentation devices or at least one refreshable braille display devices.
7. A method, comprising: initiating, by an expression converter, a multi-user interactive math computing session including at least one refreshable braille display device and at least one visual presentation device; receiving, by the expression converter, math input data representing a presentation markup representation of a mathematical expression during the multi-user interactive math computing session; converting, by the expression converter, the math input data representing the presentation markup representation of the mathematical expression to a mathematical markup language (MathML) representation of the mathematical expression, using a first set of data conversion rules for converting presentation markup of mathematical expressions to MathML; converting, by the expression converter, the MathML representation of the mathematical expression to a set of braille output math characters, using a second set of data conversion rules for converting MathML to braille math output, wherein the set of braille math output characters includes at least one braille mathematical symbol that does not correspond to any character in the received input data or in the MathML representation of the mathematical expression; transmitting, by the expression converter, the set of braille output characters to the at least one refreshable braille display device, wherein the converting and transmitting of the braille output math characters is performed in real-time in response to the receiving the math input data representing the presentation markup representation of the mathematical expression, receiving, by the expression convertor, a plurality of single-character revisions to the mathematical expression during the multi-user interactive math computing session, including at least a first single-character revision received as braille math input from the at least one refreshable braille display device, and a second single-character revision received as presentation markup math input from the at least one visual presentation device; and in response to each of the plurality of single-character revisions to the mathematical expression received during the multi-user interactive math computing session; (a) determining an input data type of the received single-character revision to the mathematical expression; (b) determining a set of conversion rules for converting the revised mathematical expression to MathML, based on the determined input data type; (c) converting the revised mathematical expression incorporating the single-character revision into revised MathML of the mathematical expression, using the determined set of conversion rules; (d) converting the revised MathML of the mathematical expression into one or more output math formats comprising at least one of braille math output or presentation markup math output; and (e) transmitting the revised mathematical expression, converted into the one or more output math formats to one or more output devices including at least one of the visual presentation devices or at least one refreshable braille display devices. 10. The method of claim 7 , wherein converting the MathML representation of the mathematical expression to the set of braille output math characters using the second set of data conversion rules comprises: applying character mapping rules to the MathML representation of the mathematical expression, to generate a corresponding string of braille characters; analyzing the generated string of braille characters to detect one or more predetermined character patterns; and using the at least one braille encoding rule that does not correspond to a character mapping rule, to convert the one or more predetermined characters patterns in the generated string of braille characters.