What is Backus-Naur Form??
A formal notation used to describe the syntax rules of a language.
What type of languages can’t be expressed by a regular expression??
Context-free languages.
What does ::= mean in BNF??
Is defined as.
What does | mean in BNF??
Or.
What does <> mean in BNF??
Specifys a category.
What do two symbols side by side mean in BNF??
That one symbol must follow the other.
What is a terminal symbol in BNF??
A symbol that can’t be broken further down.
What is a non-terminal symbol in BNF??
A symbol that can be further broken down.
What does it look like to define a “digit” category in BNF??
<digit> ::= 0|1|2|3|4|5|6|7|8|9
How would you define a postcode category as two uppercase letters followed by two digits??
<postcode> ::= <upper><upper><digit><digit>
In ab|cd, is it ab OR cd or a (b OR c) d??
ab OR cd
Why is BNF used for programming languages??
Because the instructions for a computer must not be ambiguous in any way.
What is a single BNF statement called??
A production rule.
2021-01-21
How could you write a <number> category that’s made of a <digit>??
<number> ::= <digit>|<digit><number>
What does $1234$ match??
valueterm
What does $0 + A$ match??
sum
What does $XY$ match??
Nothing, not defined.
What does $X + Y + 3 + 1$ match??
sum
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Metadata
date: 2021-01-19 10:08
tags:
- '@?computing'
- '@?regular-languages'
- '@?public'
title: Computing - Backus-Naur Form
