August 23, 2024
P46 - Truth tables for logical expressions.
Define functions and, or, nand, nor, xor, impl, and equ (for logical equivalence) which return true or false according to the result of their respective operations; e.g. and(A, B) is true if and only if both A and Bare true.
> p46:l_and(true, false).
false
> p46:l_or(true, false).
trueerlang
-module(p46).
-export([l_and/2, l_or/2, l_nand/2, l_nor/2, l_xor/2, l_impl/2, l_equ/2, table2/1]).
l_and(false, _) -> false;
l_and(_, false) -> false;
l_and(true, true) -> true.
l_not(true) -> false;
l_not(false) -> true.
l_or(false, false) -> false;
l_or(_, _) -> true.
l_nand(A, B) -> l_not(l_and(A,B)).
l_nor(A, B) -> l_not(l_or(A, B)).
l_xor(A, B) ->
case {A, B} of
{True, True} -> false;
{False, False} -> false;
{True, False} -> true;
{False, True} -> true
end.
l_impl(X, Y) ->
case[X,Y] of
[true, false] -> false;
_ -> true
end.
l_equ(X, X) -> true;
l_equ(X, Y) -> false.
table2(Fun) ->
io:format("A B result~n"),
io:format("true true ~w~n", [Fun(true, true)]),
io:format("true false ~w~n", [Fun(true, false)]),
io:format("false true ~w~n", [Fun(false, true)]),
io:format("false false ~w~n", [Fun(false, false)]).
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