SYNTHESIZING UNION TABLES FROM THE WEB

Systems and techniques are provided for generating a union table with from stitchable tables. Tables may be extracted from web pages to obtain extracted tables. Stitchable tables may be determined from the extracted tables. Hidden attributes for the stitchable tables may be extracted from the web pages from which the stitchable tables were extracted using segmentation of text for contextual data from the web pages into segment sequences, and alignment of the segment sequences. Iterative pairwise alignment may be used to align the segment sequences and obtain aligned segments. The stitchable tables may be joined into a union table. Hidden attributes from the aligned segments may be added to the union table. Headers for the hidden attributes in the union table may be labeled using a database of entities and class labels.