computer science

Webgraph

Webgraph is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Webgraph rather than just read about it. In short: A webgraph is a set of directed links between pages of the World Wide Web. A graph, in general, consists of several vertices, some pairs connected by edges.

Key takeaways

Webgraph belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Webgraph to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Webgraph from memory before moving on to harder problems.

Reference excerpt

A webgraph is a set of directed links between pages of the World Wide Web. A graph, in general, consists of several vertices, some pairs connected by edges. In a directed graph, edges are directed lines or arcs. The webgraph is a directed graph, whose vertices correspond to the pages of the WWW, and a directed edge connects page X to page Y if there exists a hyperlink on page X, referring to page Y.

Properties The degree distribution of the webgraph strongly differs from the degree distribution of the classical random graph model, the Erdős–Rényi model: in the Erdős–Rényi model, there are very few large degree nodes, relative to the webgraph's degree distribution. The precise distribution is unclear, however: it is relatively well described by a lognormal distribution, as well as the Barabási–Albert model for power laws. The webgraph is an example of a scale-free network.

Applications The webgraph is used for:

computing the PageRank of the world wide web's pages; computing the personalized PageRank; detecting webpages of similar topics, through graph-theoretical properties only, like co-citation; and identifying hubs and authorities in the web for HITS algorithm.

References

External links Webgraphs in Yahoo Sandbox Webgraphs at University of Milano – Laboratory for Web Algorithmics Webgraphs at Stanford – SNAP Webgraph at the Erdős Webgraph Server Web Data Commons - Hyperlink Graph

Worked examples

Example 1 — a first encounter with Webgraph

Start with the simplest possible case. Write down what Webgraph claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Webgraph before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Webgraph ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Webgraph

In research: Webgraph appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Webgraph in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Webgraph is common in secondary-school and first-year university syllabi. It links to neighbouring topics Application-specific graphs, Internet search algorithms, so understanding it makes those chapters shorter.
In everyday life: Look for Webgraph outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Webgraph in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Webgraph means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Webgraph out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Webgraph in simple terms?

A webgraph is a set of directed links between pages of the World Wide Web. A graph, in general, consists of several vertices, some pairs connected by edges.

Why does Webgraph matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Webgraph?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Webgraph.