Linear lists

In looking at Figures 1-7, it is obvious that the rows formed by the assemblage of attendees were a bit free-form. The names in the figure captions are based on the sign-up sheets that were distributed at the time of the photography. A row-by-row correspondence between the distribution on faces and the linear list of names is impossible in many cases. However, the faces and names... 

In order to derive general sequence lists we must be able to express the necessary functionality which is to lie on the hnear strand of carbons passing through the construction sites on any of these 13 synthon patterns of Fig. 3. This can be done by a linear list of f-values for the involved carbons, first as starting materials, then as products. The basis for this lies in the codification of the involved functionahty in construction reactions, developed in Ref. and summarized in this section. 

Another important consideration is that if we are going to use an HMM based labeller, then it makes sense to use a sound representation system which is amenable to HMM labelling. In general this means adopting a system which represents speech sounds as a linear list, and unfortunately precludes some of the more sophisticated non-linear phonologies described in Section 7.4.3. 

Linear list One-dimensional data set in which relative order is important. In mathematical terms, linear list elements are totally ordered. 

Queue Linear list with two ports, one for inputs the other for outputs data structure supporting algorithms that operate in a first-in-first-out manner. 

Stack One-port linear list that operates in a last-in-first-out manner. This structure is heavily used to implement recursion. 

Descriptions of the simplest data structure entities and explanations of their nature follow in succeeding sections. Basic data structures are stack, queue, and other linear lists multiple-dimension arrays (recursive) lists and trees (including forests and binary trees). Pointer or link simply means computer data constituting a memory location. Level indicates position in a structure that is hierarchical. Link, level, and the elementary structures are almost intuitive concepts. They are fairly easily understood by reference to their names or to real-life situations to which they relate. Evolving computer practice has had two effects. First, the impact of the World Wide Web and Internet browsers has acquainted many computer users with two basic ideas link (pointer) and level. Second, computer specialists have increased their use of advanced data structures. These may be understandable from their names or descriptive properties. Some of these terms are tries, quad-trees (quadtrees, quaternary trees), leftist-trees, 2-3 trees, binary search trees, and heap. While they are less common data structures and unlikely to be part of a first course in the field, they enable algorithmic procedures in applications such as image transmission, geographic data, and library search. 

In data structure terms, all these outputs are lists, but the last item is more. In ordinary terms, it is an organization chart. That is a special kind of data stmcture possessing hierarchy. As a data structure, the relationship possesses a hierarchical quality so it is not just a list but also a tree. Trees can be represented by a linear list data structure through the use of a special place marker that signifies change hierarchy level. In text representation, either a period or a parenthesis is used for that purpose. Whether a data structure is a list or is represented by a list is another of the unusual aspects of this field of knowledge. Nevertheless, these are just two aspects of the problem being dealt with, specifically ... 

Simple sequential assignment of memory can implement list structures. Three elementary data structures are illustrated as follows by list examples. A pile of papers on a desk is a stack. A group of cars in a one-lane traffic bottleneck is a queue. A collection of candies can be a bag. Actually, in computer terms the data objects (papers, cars, and candies) are stored in the named data structure, and all three are generally called linear lists. The data type (e.g., real, integer, complex) is another attribute that must be noted in planning the data structure. It can change the space needed by each node (complex values require more bits). 

Trees may be ordered that is, all the children of any node in the structure ai e indexed (first, second, etc.). An ordered tree is the most common kind used in computer programs because it is easily represented by a binary tree within each sibling set is a linear-list-like structure, which is useful for data retrieval a nonordered tree is much like a... 

Strings, linear lists with space markers added, are often used to give text depictions of trees. There are several ways to visually depict the hierarchical relationship expressed by tree structures nested parentheses, bar indentation, set inclusion, and decimal points—essentially the same device used when library contents are organized, for example, by the Dewey decimal system. All of these methods can be useful. The kind of information that can be stored by a tree data structure is both varied and often needed in practical situations. For example, a tree can describe the chapter outline of a book (Fig. 2a). On personal computers or web browsers, the starting location is called the root or home. It lists highest level information. 

Two kinds of simple lists are stacks and queues. A stack is a data store where both input and output occur at the same location the general name for such a place is a port. Stacks are characterized by last-in-first-out data handling. A queue is a two-port store characterized by first-in-first-out data handling. A queue is a more versatile data structure than a stack. A method for storing a queue in a fixed fast memory space uses circular wrapping of the data (modulo storage). There is another kind of linear list—a deque or double-ended queue, which has two ports. In the most general deque, input and output can take place at both ports. 

Linear lists are data structures with entries related only through their one-dimensional relative positions. Because of this, from size and starting location of the structure, both first and last nodes can be located easily. 

A tracked interface is a collection of geometric objects describing the location of a set of fronts at a given time. They consist of discrete representations of points, curves and surfaces. A curve is a connected oriented piecewise linear list of bonds, which are connectors between adjacent points. A surface is a connected oriented piecewise... 

In the case of pivot or cut-and-paste moves, one maintains two linear lists—one active and one scratch —together with a flag saying which is currently which. The coordinates of a proposed new walk are successively calculated and placed in the scratch list, and self-avoidance is simultaneously tested (see Section 2.7.1.2) if the self-avoidance test is passed, the flag is flipped and the scratch list now becomes active . 

To get the virtues of both sequential allocation and linked list, one can use a contiguously allocated doubly linked linear list (see e.g., Ref. 132, Section 3.3). That is, the walk coordinates are stored in a contiguous array (Olilo but not in any particular order, that is, s i) is some site of the walk, but not necessarily w,. To keep track of the sequence of steps along the walk, we use forward pointers (i) /Io backward pointers (i) o> (0... 

The top level of architecture (Table 4) of this very large data collection is fundamentally different in its data structure from the Beilstein Handbook, or the Beilstein file at STN or DIALOG, which have never claimed to be reaction- or document-oriented, and are simple linear lists. It is ultimately responsible for the unifying hyperlink philosophy in CrossFire, which contains upwards of 50 million hyperlinks (see below). 

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