The aim of the present notes is to describe an algorithm for the syllabification of written Italian that has
been developed at Laboratorio di Linguistica. The present algorithm is of deterministic type and it is based upon
the use of recursion and of binary tree in order to detect the boundaries of the syllables within each word

Cioni, Lorenzo

The aim of the present notes is to describe an algorithm for the syllabification of written Italian that has
been developed at Laboratorio di Linguistica. The present algorithm is of deterministic type and it is based upon
the use of recursion and of binary tree in order to detect the boundaries of the syllables within each word

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98Lorenzo CioniAn algorithm for the syllabification of written Italian("V Simposio Internacional de Comunicacin Social", Santiago de Cuba, January 22-24 1997)AbstractThe aim of the present notes is to describe an algorithm for the syllabification of written Italian that hasbeen developed at Laboratorio di Linguistica. The present algorithm is of deterministic type and it is based uponthe use of recursion and of binary tree in order to detect the boundaries of the syllables within each word.IntroductionThe aim of these notes is to describe an algorithm for the syllabification of written Italian thathas been developed by the author at Laboratorio di Linguistica.The scope of such an algorithm is that of assigning the syllable boundaries to orthographicrepresentations of written Italian.The outcome of the algorithm is the production of the so-called canonical syllabification, i.e.the one either defined by the rules of grammar or on which the most of the people agree, of thewords it receives as an input stream (see the implementation notes).This means that the algorithm produces the hyphenated version of each word, where eachhyphen marks the presence of a syllable boundary. At the present phase of design, thealgorithm produces each hyphenated word by examining a set of rules in a very particular way,that we are going to state more precisely soon, but a morphological pre-processing module isunder study.Such a module should allow the algorithm to avoid as many errors as possible such thosethat, at the present, occur in presence of prefixes.Indeed, for the time being, the algorithm, by applying the rules, behaves in a way such that,for instance, a word like biologia (biology, bio is the prefix meaning life) is correctlyhyphenated as bio-lo-gia whereas a word with a similar structure such as biossido (dioxide, biis the prefix meaning double) is hyphenated as bios-si-do and not according to the canonicalform bi-os-si-do.Last but not least, we note that we aim at obtaining the correct hyphenation of Italian wordby using a minimal set of rules. It is obvious, indeed, that by defining an ordered set of pairsword/hyphenated-string and by executing for a certain word a binary search we obtain easilyand quickly (in log n steps for n pairs) the desired syllabification.We can define such an approach as the n-words/n-rules approach and moreover it is easilyunderstood that if we have enough rules arranged in some way we are able to correctlyhyphenate as many words as we need.What we are trying to do is to achieve the same result with a fixed and small set of rules.The syllabification rulesThe algorithm, by means of an abstract computational structure (a binary decision tree),implements a set of syllabification rules that are shortly outlined in what follows. We note thatC denotes a generic consonant whereas V represents one of the five vowels of written Italian(a, e, i, o, u).The main accent is explicitly marked on the right of the corresponding vowel by using thecharacter '.We note that the presence of the accent is necessary in some cases to get the correctsyllabification and that it does not alter the binary structure of the decision tree since in any casewe have a choice consonant-vowel or consonant-accented vowel and so a double choice thatallows us to define more correct syllabification rules.For instance, if we have a non accented word like baule (trunk) from the rules we get thewrong syllabification bau-le instead of the correct one ba-u-le that the algorithm produces if wespecify the position of the accent and so if the input string is bau'le. The same holds in case ofpaura and pau'ra (fear).We now examine the rules. The first rule states that whenever there is a combination of theform CVCV the algorithm produces the syllabification CV-CV by inserting an hyphen in thecorrect position. This occurs independently from the presence of accented vowels, as in theother cases that follow.Another rule states that the group V1C1C2V2 is syllabified as:99- V1C1-C2V2 if C1 = C2- V1-C1C2V2 if C2 = h- V1-C1C2V2 if C2 = l or r and C1 ≠ l and r- V1s-C2V2 or V1-sC2V2 if C2 ≠ s- V1C1-C2V2 in any other case. The open case must be solved depending on the nature of C2.The group V1C1C2C3V2 is syllabified as V1C1-C2C3V2 but if C1= s we can get eitherV1C1-C2C3V2 or V1-C1C2C3V2 depending on C2 and C3. The present rule has someexceptions represented y prefixed words such as transcaucasico (trans-caucasian) that must besyllabified as trans-cau-ca-si-co and postdatare (post-date) as post-da-ta-re.We think, however, that such kind of exceptions should be examined from a morphologicalperspective and therefore that an algorithm based on the examination of a word as a sequence ofconsonants and vowels can make such mistakes without being considered as completelywrong. To reduce the percentage of errors a morphological module, for instance, should markthe presence of prefixes so that the algorithm would act as in presence of two words to beindividually syllabified.At last, the group V1C1C2C3C4V2 is syllabified as V1C1C2-C3C4V2 though there areexceptions such as the word substrato (substratum) that must be syllabified as sub-stra-to.The presence of group of vowels makes the syllabification harder since in Italian we canhave up to six consecutive vowels (as in cuoiaio to be syllabified as cuo-ia-io, a person whosells or tans leather) though no more than three vowels can be contained in a single syllable.The algorithm, in presence of three or more consecutive vowels, tries therefore to analyse suchgroups of vowels looking, as a first resort, for triphthongs and then for diphthongs. Anywaywe present in what follows some of the rules we have used in case of two consecutive vowels.Vowels like a, e and o when are one after the other (like ae, ao and the like) never belong tothe same syllable. In a group like quV the vowel u form always a diphthong with V, where Vcan be a, e, i or o. We have diphthongs in cases such as- V1V'2 where either V1 = i and V2 = a, e, o or u or V1 = u and V2 = a, e, o or i- V1'V2 where either V2 = i and V1 = a, e, o or u or V2 = u and V1 = a, e, o or i- V1V2 where either V1 = i and V2 = a, e, o or u or V1 = u and V2 = a, e, o or i- V1V2 where either V2 = i and V1 = a, e, o or u or V2 = u and V1 = a, e, o or iSuch rules present many exceptions such as coincidenza (coincidence) to e syllabified as co-in-ci-den-za and semiasse (axle shaft) to be syllabified as se-mi-as-se and many more but forthese exceptions we refer to our past considerations.As to groups of three or more consecutive vowels the algorithm scans a such group from leftto right and examines the first three vowels it finds so to identify the position of the syllableboundary and to skip to the next character to be examined.At this point  there can be two cases:- the three vowels form a triphthong so that they can be considered a single character or- they do not form a triphthong and so the group of vowels must contain the syllable boundary.In the first case the character that follows the triphthong can be either a vowel or aconsonant. If it is a vowel, the algorithm puts the syllable boundary immediately on the left ofthe triphthong and starts another recursive cycle, if it is the case. If it is a consonant, thealgorithm pre-loads the first two vowels on the output stream and another recursive cycle starts,with a vowel (followed by a consonant) as the current position. The algorithm, however,consider the definition of a group of three vowels as a triphthong as a hard problem so it uses apre-load technique (see below) to handle such a situation.In the second case there are the following possibilities: V1V2V3 is either syllabified as V1-V2V3 or as V1V2-V3 where only one of the Vi can be accented. If the group does not containany accented vowel the algorithm behaves according to the following rules:- if V1 = a, o or e then it produces V1-V2V3;- if V1 = i and V2 ≠ u then it produces V1V2-V3;- if V1 = u and V2 ≠ i then it produces V1V2-V3;- if V1 = i and V2 = u or V1 = u and V2 = i then it pre-loads V1 and restarts with V2 as currentposition. We have defined similar rules in cases in which there is an accented vowel. The firstof the aforesaid rules accounts for soia (soybean) as so-ia, the second for ghiaia (gravel) asghia-ia and so on.The structure of the algorithmThe algorithm is of deterministic type and it is based upon the use of recursion and of binarytree in order to detect the boundaries of the syllables within each word.100The algorithm is composed by a set of modules that handle the input of words to besyllabified either from keyboard or from a file, the output of the stream of syllables either onthe screen or on a file and implement the binary decision tree.Such a tree is obviously not complete owing to the structure of the real Italian words and isbinary since each node has two children (a consonant or  vowel or a consonant and an accentedvowel) or is itself a leaf. The aim of the algorithm is that of defining a path from the root to aleaf to which corresponds a syllabification rule that allows the definition of a syllable boundary.The tree is dinamically created in this way. The starting point is a non-labelled root. The firstcharacter locates one of the two possible children and so does the second, the third and so ontill the algorithm does not reach a leaf whose associated rule defines which is the inner nodethat represents a syllable boundary. The word, not always meaningful, is then split up in twoparts: a syllable and a new word on which the algorithm is applied again whereas the syllable isput on the output stream.The process goes on till the last syllable is reached. This characteristic defines the algorithmas recursive.We note that each of the leaves defines a syllabification rule and represents the place wherepossible exceptions and indefinite cases are dealt with.The morphological module should act as either a pre-processor (so to examine the originalnot syllabified word and, for instance, insert a marker that points out the presence of a prefix sothat the algorithm can handle the incoming exception) or a post-processor so to examine theoutcome and check if the syllabification gave rise to errors (this is very important during adebugging phase).Now we pass at the analysis of some examples of pre-processing. Let us suppose to have aword like postromantico (post-romantic) and a word like postribolo (brothel). Without pre-processing, the first word would be syllabified as po-stro-man-ti-co whereas post represents inthis case a prefix and so the correct syllabification is post-ro-man-ti-co. For the other wordthere is no problem since there is no prefix and the correct syllabification is po-stri-bo-lo.In the first case a pre-processor would insert a marker so to produce post*romantic so thatno error would occur.Some simple examplesLet us start with a simple example, the word calamita (magnet) that is very easy to syllabifybut that will help us at introducing the way the algorithm behaves.The algorithm scans the word from left to right and when reaches the second a finds itself ona leaf to which corresponds the rule CVCV ® CV-CV and so it splits up the word in two parts:the syllable ca and the meaningless word lamita.The algorithm is applied again on lamita so to produce la and mita and again on mita so toproduce mi and ta. At this point the processing stops and the algorithm produces a stream ofsyllables with hyphens in the correct positions: ca-la-mi-ta.From the above example, it is easily understood that the algorithm uses some simpletechniques of look-ahead so to scan the word on the right of the current position and define asyllable boundary, moreover at each node on the tree it pre-load as many characters as it can onthe output stream so to speed up the process.We note that the knowledge of a certain number of characters on the right of the currentposition is necessary to locate a syllable boundary whereas whenever the algorithm reaches aninner node some of the characters on the left may be unnecessary and can be stripped andloaded on the output stream.As another example we take the word carro (wagon). In order to define the first (and only)syllable boundary the algorithm scans the word to the end so to find the leaf with the ruleV1C1C2V2 ® V1C1-C2V2 since the two consonants are identical but when examines C1 it canpre-load C0 = c and when examines C2 it can pre-load V1= aLikewise the algorithm syllabifies words such as lento (slow) to give len-to orprecipitevolissimevolmente (very very fast, the longest word of written Italian) to give pre-ci-pi-te-vo-lis-si-me-vol-men-te.Let us consider some harder example such as cuoiaio. The algorithm scans the word fromthe left till it finds a group of three vowels uoi that cannot form a triphthong so it uses theproper rule and splits the triple as uo-i, then it goes on with scanning and find three morevowels iai that once again cannot belong to the same syllable and so, with another rule, it splits101them as ia-i. At this point the algorithm finds two vowels that are known to form a diphthongand so can produce the syllabified version of the original word: cuo-ia-io.Other examples are ghiaia (gravel) as ghia-ia, aiuola (flowerbed) as a-iuo-la  and troiaio(pigsty) as tro-ia-io.Implementation notesThe program that implements the algorithm has been written down with ANSI C on aworkstation Digital Alpha 3000/300 with Digital Unix 3.2C. The use of ANSI C should ensureits full portability.The program has been designed so to accept input data both from keyboard and from a textfile and to produce the stream of syllabified words both on the screen and on a file.Last but not least it can be composed with other commands according to the Unixphilosophy so to be used in conjunction, for instance, with a module that analyses themorphology of the words to be syllabified and that is currently under development.AcknowledgementsThe author wishes to thank Professor Pier Marco Bertinetto and Doctor Maddalena Agonigifor many of the syllabification rules on which the algorithm is based.BibliographyCioni, L. (1996), "RB-tree: un algoritmo per la sillabazione dell'italiano", proceedings of XXIV ConvegnoNazionale dell'Associazione Italiana di Acustica, Trento, 12-14 June 1996:145-148.Daelemans W & A. van den Bosh, "Generalization performance of backpropagation learning on a syllabificationtask", other data missing.Laks B., (1995), "A connectionist account of French syllabification", Lingua 95:51-76

An algorithm for the syllabification of written Italian

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An algorithm for the syllabification of written Italian

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