This parser uses the notation which is a bit inspired by programming
languages like Javascript and C. The notation for the logical connectives
and constants used are the following ones:
- brackets ( and ) are used,
- 0 and 1 are the logical constants,
- A, B, ..., Z are the logical atoms,
- & means "and",
- | means "or",
- + means "exclusive or",
- ! means "not",
- > means "implies (->)",
- < means "is implied by (<-)",
- = means "is equilvalent to (<->)".

The symbols from the textbook
are not available in the ASCII character set
or cannot be typed easily on a keyboard.
All variables are predefined as 0 and one can
input statements of the form
in order to assign new values to variables.
The parser parses these statements including the formula
on the right side of the assignment and informs if there is an error.
The empty input terminates the process.

You can view the program with your browser (at Firefox: Web developper
tools and then View source) and read on the internet about the used
programming language Javascript.