week1.erl

-module(week1).
-export([xOr_first_impl/2, xOr_second_impl/2, xOr_third_impl/2, maxThree/3, howManyEqual/3
, test_howManyEqual_function/0, test_maxThree_function/0, test_xOrImpl_function/0]).



%xOr implementations.
xOr_first_impl(A, B) ->
    A =/= B.

xOr_second_impl(A, B) ->
    not (A == B).

xOr_third_impl(A, B) ->
   (not A and B) or (A and not B).


%max of three numbers
maxThree(First, Second, Third) ->
    max(First, max(Second, Third)).


%Number Equal arguments in three
howManyEqual(First, First, First) ->
    3;
howManyEqual(First, First, _) ->
    2;
howManyEqual(First, _, First) ->
    2;
howManyEqual(_, First, First) ->
    2;
howManyEqual(_, _, _) ->
    0.

%
%test functions
%
test_howManyEqual_function() ->
    (howManyEqual(3,3,3) == 3) and
    (howManyEqual(1,3,3) == 2) and
    (howManyEqual(3,1,3) == 2) and
    (howManyEqual(3,3,1) == 2) and
    (howManyEqual(1,2,3) == 0).

test_maxThree_function() ->
    (maxThree(1,2,3) == 3) and
    (maxThree(1,1,1) == 1) and
    (maxThree(-1, 0, -2) == 0).

test_xOrImpl_function() ->
    (xOr_first_impl(true, false) == true) and
    (xOr_first_impl(true, true) == false) and
    (xOr_first_impl(false, true) == true).

A good solution.
Stylistic Tip: It's more common in Erlang to use snake_case, instead of pascalCase for functions, modules, and atoms in general.