science

Tabled logic programming

Tabled logic programming is a 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 Tabled logic programming rather than just read about it. In short: Tabling is a technique first developed for natural language processing, where it was called Earley parsing. It consists of storing in a table (a.k.a. chart in the context of parsing) partial successful analyses that might come in handy for future reuse.

Key takeaways

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

Reference excerpt

Tabling is a technique first developed for natural language processing, where it was called Earley parsing. It consists of storing in a table (a.k.a. chart in the context of parsing) partial successful analyses that might come in handy for future reuse. Tabling consists of maintaining a table of goals that are called during execution, along with their answers, and then using the answers directly when the same goal is subsequently called. Tabling gives a guarantee of total correctness for any (pure) Prolog program without function symbols. Tabling can be extended in various directions. It can support recursive predicates through SLG resolution or linear tabling. In a multi-threaded Prolog system tabling results could be kept private to a thread or shared among all threads. And in incremental tabling, tabling might react to changes.

History The adaptation of tabling into a logic programming proof procedure, under the name of Earley deduction, dates from an unpublished note from 1975 by David H.D. Warren. An interpretation method based on tabling was later developed by Tamaki and Sato, modelled as a refinement of SLD-resolution. David S. Warren and his students adopted this technique with the motivation of changing Prolog’s semantics from the completion semantics to the minimal model semantics. Tabled Prolog was first introduced in XSB. This resulted in a complete implementation of the well-founded semantics, a three-valued semantics that represents values for true, false and unknown.

References

This article incorporates text from this source, which is by PHILIPP KÖRNER, MICHAEL LEUSCHEL, JOÃO BARBOSA, VÍTOR SANTOS COSTA, VERÓNICA DAHL, MANUEL V. HERMENEGILDO, JOSE F. MORALES, JAN WIELEMAKER, DANIEL DIAZ, SALVADOR ABREU and GIOVANNI CIATTO available under the CC BY 4.0 license.

Worked examples

Example 1 — a first encounter with Tabled logic programming

Start with the simplest possible case. Write down what Tabled logic programming claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Tabled logic programming 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 Tabled logic programming 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 Tabled logic programming

In research: Tabled logic programming appears in 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 Tabled logic programming 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: Tabled logic programming is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dynamic programming, Logic programming, Programming language topic stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Tabled logic programming 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 Tabled logic programming in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tabled logic programming 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 Tabled logic programming out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tabled logic programming in simple terms?

Why does Tabled logic programming matter?

Because it connects several 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 Tabled logic programming?

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 Tabled logic programming.