1. A computing system for handwritten mathematical expression recognition, the computing system comprising: a component configured to receive from a user a handwritten mathematical expression; a component configured to receive from the user a selection of a dominant symbol within the handwritten mathematical expression; a subordinate sub-expression analysis component configured: to identify sub-expression information for the dominant symbol within a handwritten mathematical expression, the dominant symbol having shape information, and to recognize a character that the dominant symbol represents based on shape information of the dominant symbol and the identified sub-expression information, the sub-expression information including location of sub-expressions relative to the dominant symbol; and a component configured to display to the user a list of one or more characters that the dominant symbol represents and receive from the user a selection of a character from the list; a component configured to display to the user the selected character to replace the dominant symbol in the handwritten mathematical expression along with a placeholder corresponding to a sub-expression of the selected character; and a component configured to receive from the user a symbol to be inserted in the placeholder, the symbol representing a sub-expression of the selected character the components being implemented as computer-executable instructions stored in memory of the computing system for execution by a processing unit of the computing system.