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82 The bank vole lives in hedgerows. The wood mouse lives in woodlands. We need to generate the HTML by transforming the original XML. We do this using the following XSLT document: The lives in . Don't worry about the shaded parts at the top and bottom. The main part consists of two XSLT template elements. The text in bold relates to XSLT, the rest is sent to the output file just as it appears. The first template element prints out some HTML to the output document, and calls the second template. This second template prints out some English words plus the content of the english_name and habitat elements in the original document. It does this for each species_description element in the original XML document. Note that an XSLT document is also expressed in XML syntax! A2.3 Prolog Prolog (programming in logic) is a computer language developed in the 70's for representing and reasoning with statements expressed in first-order predicate logic, a form of logic that is both expressive (it can handle a rich variety of logical statements) while at the same time having welldefined formal properties. Prolog is a declarative programming language: rather than giving the computer instructions, as in a conventional procedural or imperative programming language, you state facts and rules about some area of knowledge. Instead of 'running a program' to solve a problem, you 'enter a query', and the Prolog interpreter then tries to use the facts and rules to solve the problem. Here is an example Prolog program:
83 eats(bank_vole,seeds). eats(bank_vole,berries). eats(wood_mouse,seeds). eats(wood_mouse,berries). eats(wood_mouse,insects). herbivore(X):- eats(X,seeds). herbivore(X):- eats(X,berries). carnivore(X):- eats(X,insects). You probably don't think of this as a 'program'. It contains facts that you would perhaps normally expect to see in a database, and rules. The first rule, for example, is read in English as "X is a herbivore if X eats seeds", with the :- symbol being read as the word "if". We certainly can't 'run' this program. But we can ask it questions, by entering a Prolog query in response to the ?- prompt produced by the Prolog interpreter. Thus: ?- eats(bank_vole,X). In English: "What does the bank_vole eat?" returns the answer X = seeds X = berries while the question ?- carnivore(X). In English: "What is a carnivore?" returns the answer X = wood_mouse using the last rule and the 5th fact.
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1 Position Paper on Declarative Mod
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3 8.3 Exploiting the declarative na
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5 15. It is argued that the efficie
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7 another for comparing the structu
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9 • Programs for research-grade m
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11 3.2 Modular modelling, component
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13 into the correct order. In some
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15 LAMOS: Landscape Modelling Shell
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17 5. What does 'declarative' mean?
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19 and write a generic program whic
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21 functions that can calculate vol
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23 5.5 What are the benefits of gre
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25 6.2 Mathematical description The
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27 6.4 Representation of the model
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29 6.6 Representation of the model
Page 31 and 32: 31 6.8 Representation of the model
Page 33 and 34: 33 7. Architecture for a declarativ
Page 35 and 36: 35 7.2 Designing the model-represen
Page 37 and 38: 37 Figure 7.1 is a partial view of
Page 39 and 40: 39 context of spatial modelling). T
Page 41 and 42: 41 ensure that the various packages
Page 43 and 44: 43 and run as a stand-alone model (
Page 45 and 46: 45 Desktop temperature = graph(time
Page 47 and 48: 47 generates a procedural version o
Page 49 and 50: 49 Example 2: Generating audio desc
Page 51 and 52: 51 8.4 Conclusions The aims of this
Page 53 and 54: 53 Sector Ecosystem services Indica
Page 55 and 56: 55 The XML model documents will be
Page 57 and 58: 57 Note the difference between a de
Page 59 and 60: 59 process must be clarity and rigo
Page 61 and 62: 61 product. The other, considered i
Page 63 and 64: 63 11. Critical evaluation of the d
Page 65 and 66: 65 Restriction to scientific freedo
Page 67 and 68: 67 are, for example, initiatives to
Page 69 and 70: 69 Acknowledgements and declaration
Page 71 and 72: 71 Forrester, J.W. (1971) World Dyn
Page 73 and 74: 73 URLs: (Web links) ACSL Advanced
Page 75 and 76: 75 Glossary See "URLs: Web links" a
Page 77 and 78: 77 Appendix 1. The Modelica, MODCOM
Page 79 and 80: 79 Appendix 2. A brief introduction
Page 81: 81 bank vole Clethrionomys glareol
Page 85: 85 Modelica .......................
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