lulgician Manual

lulgician is a little utility that handles Discrete Linguistics stuff.

Building

Building the main program:

gcc lulgician.c -O2 -o lulgician

Building the test suite:

gcc test.c -O2 -o test

Note: keep the testcases.txt and the executable test under the same directory.

Running

Usage: ./logic [d|t], where:

• d: digest only
• t: truth table mode

No arguments: Expression mode (verbose)

Analyses a given infix logical expression. Prints a truth table, a CNF and a DNF.

Possible atomic propositions are the 26 English letters and are case insensitive. Among them, T is assigned ⊤ and F is assigned ⊥, and the remaining 24 are variable.

All whitespaces identifiable by the isspace standard library function will be ignored.

Supported operators, in descending precedence:

• Negation (Not): !
• Conjunction (And): &
• Disjunction (Or): |
• Material conditional (Implies): ^ or >
• Material equivalence (Iff): ~ or =

All operators except Negation are left associative; that is, a~b~c will be interpreted as (a~b)~c (contrary to some conventions where it's right associative).

Negation is the only unary operator and is a prefix notation.

The order for the variable assignments in the truth table is a binary counter with each bit assigned to a variable in opposite orders of bit significance and lexicographic ranks of variable names.

d: Expression mode (digest only)

Digest-only mode produces a more machine-readable output. It produces a string of 0's and 1's representing each row in the truth table. The order is the same as that in verbose mode.

t: Truth table mode

Produces a valid logical expression given a truth table in the format of digest-only mode's output.

The input should consist of two lines: the first should contain an integer N between 1 and 24 (inclusive) denoting the number of variables; the second should contain a binary string of 2^N characters representing the truth table.

Variable names are allocated in increasing lexicographic order; T and F are skipped.

The expression is only guaranteed to be valid; it's usually far longer than is necessary.

Test suite

Usage: ./test [<program> [<cases-file>]]

• <program>: the path to the executable to be tested, defaults to ./a.out;
• <cases-file>: the path to the file containing all test cases, defaults to testcases.txt.

The format for a test case is a line containing an expression followed by the expected truth table produced in digest mode. Lines starting with a # character are ignored and do not interrupt a two-line pair. Empty lines are not ignored.

In case of Mozibake, comment the change_colour() implementation and re-compile. The most probable cause is that the terminal does not recognize ANSI escape codes, as is the case with Windows CMD before Windows 10 TH2.