Introduction
Conventional Arabic OCR systems are based on a typographic perception of script, assuming that glyphs, the units of mechanical reproduction of script, have a logical relation with graphemes, the units of script itself. Current methods try to recognise script by splitting chunks of text into paragraphs, paragraphs into lines, lines into words, and words into characters or sub-characters (Srihari and Ball 2014: 7-8). This approach follows the traditional mechanics of the 15th century printing press, where actual shapes of letters or groups of letters are represented in types or sorts, i.e., in physical boxes: the glyphs of today's font technology. It inadvertently treats the glyph as the smallest unit of Arabic script, whereas in reality, glyphs are not. For example, it is quite usual in manuscripts to find a grapheme compound ب, there the base grapheme ٮ B and the dot grapheme are not in the same physical space, but the dot grapheme may appear in a nearby area. An example...