1. A system with a processor and a memory for symbol grouping and recognition of a handwritten mathematical expression, the system comprising: a symbol grouping component configured to group input strokes corresponding to a handwritten mathematical expression into symbols based upon intra-group and inter-group information associated with the input strokes; and a symbol recognition component configured to recognize the symbols based upon information associated with the grouped input strokes wherein the intra-group information associated with the input strokes includes a confidence representative of whether the input strokes are a certain symbol provided by the symbol recognition component, and a score representative of whether the input strokes are a valid symbol based upon intra-group spatial information that includes a size difference among the input strokes and an offset measurement among the input strokes, the score being represented by the following: f ⁢ ⁢ ( d , δ , σ ) = 1 1 + ( ( d ⁢ d 0 ) α + ( δ δ 0 ) β + ( σ σ 0 ) γ ) , ( α , β , γ > 1 ) where d represents a distance feature, δ represents a size difference feature, σ represents an offset feature, and d 0 , δ 0 , and σ 0 ; wherein the symbol grouping component is further configured to receive the input strokes, to determine intra-group spatial information among the input strokes, and to determine whether to group the input strokes into a symbol based upon the intra-group spatial; and wherein the components are implemented as computer-executable instructions stored in the memory for execution by the processor.