Final answer:
LR (Left-to-Right) is a parsing method used in computer science to analyze the syntax of a string based on a given grammar. It involves a shift and reduce phase and uses a stack and parsing tables to guide the process.
Step-by-step explanation:
In computer science, LR (Left-to-Right) refers to a parsing method used in the construction of bottom-up parsers. It is an algorithm used to analyze the syntax of a given string and determine if it can be generated by a given grammar. LR parsing involves a stack, input buffer, and a set of parsing tables that guide the process.
The LR parsing algorithm consists of two phases: shift and reduce. During the shift phase, symbols are shifted onto the stack based on the input. In the reduce phase, the algorithm reduces a portion of the stack to a non-terminal symbol based on the production rules of the grammar.
For example, consider the grammar: S -> A A, A -> a. Given the string 'aa', the LR parser will read 'a' and push it onto the stack. Then, it will read the second 'a' and reduce the stack to 'A', and finally reduce 'AA' to 'S', indicating that the string is valid according to the given grammar.