A processing device may recognize a number of input handwritten strokes, which may represent a mathematical expression, a chemical formula, or other two-dimensional structure. Rewriting rules of a grammar may be applied to the strokes to produce a number of possible recognition results. Each of the possible recognition results has a respective score based on a sum of rewriting rules applied to the strokes to produce respective ones of the possible recognition results. Input may be provided to identify misrecognized strokes and a correct terminal production, or symbol corresponding to the misrecognized strokes. Strokes may be misrecognized for many reasons, including parsing errors, over-grouping or under-grouping of matrices, and improper placement of a recognized terminal production, or symbol, with respect to a root structure. Correction hints may be leveraged for correcting types of errors mentioned above.