SUBEXPRESSION SELECTION OF EXPRESSION REPRESENTED IN CONTIGUOUS TOKENIZED POLISH REPRESENTATION

An algorithm and handheld device adapted to select a subexpression of a mathematical expression. An expression string of the handheld device is selected, and the expression string is converted to a contiguous tokenized Polish representation (CTPR) of the expression, and the CTPR of the expression is loaded into an n-ary tree. The user may navigate the visual representation of the expression to select a subexpression. The handheld device is adapted to select the subexpression from the n-ary tree.