sec multilists figure example of cyclic list the shape of the structure is directed graph this list in bracket notationwe can duplicate nodes as necessary thusthe bracket notation for the list of figure could be written hhhabiihhabicihcdeiheii for conveniencewe will adopt convention of allowing sublists and atoms to be labeledsuch as " :whenever label is repeatedthe element corresponding to that label will be substituted when we write out the list thusthe bracket notation for the list of figure could be written hhl habiihl cihl dl eihl ii cyclic list is list structure whose graph corresponds to any directed graphpossibly containing cycles figure illustrates such list labels are required to write this in bracket notation here is the notation for the list of figure hl hl hal iihl bihl cdil hl ii multilists can be implemented in number of ways most of these should be familiar from implementations suggested earlier in the book for listtreeand graph data structures one simple approach is to use an array representation this works well for chains with fixed-length elementsequivalent to the simple array-based list of we can view nested sublists as variable-length elements to use this approachwe require some indication of the beginning and end of each sublist in essencewe are using sequential tree implementation as discussed in section this should be no surprisebecause the pure list is equivalent to general tree structure unfortunatelyas with any sequential representationaccess to the nth sublist must be done sequentially from the beginning of the list because pure lists are equivalent to treeswe can also use linked allocation methods to support direct access to the list of children simple linear lists are