Diophantine Quotients and Remainders with Applications to Fermat and Pythagorean Equations ()
Keywords:
MSC2020 Mathematical Sciences Classification System: 11A05-11A07-11D41-11D72-11D75.
1. Introduction
The subject we are dealing with is within the framework of Diophantine analysis [1] . A Diophantine equation is an equation that can be solved in the domain of natural integers or at most in the domain of rational numbers [1] . The study of this type of problem is recognized as being difficult [2] . Indeed, each equation or its special cases may require its own tools to deal with them. In most cases, these tools do not seem to fit into any general theory. The focus of our study is on the Diophantine equation
with
an integer, which we name the Pythagoras’-Fermat’s equation. When
, we have the Pythagoras’ equation which admits an infinite number of parametric solutions ( [1] p. 462) [3] .
Ancient Babylonian, Greek and Egyptian mathematicians were fascinated by Pythagorean triplets, and they discovered some of them. Today, they continue to be analyzed, classified, studied to bring out new properties or algorithms for cryptographic uses [4] [5] [6] .
When
, it is the Fermat equation, and it is well known that this equation has no non-trivial solutions as demonstrated in 1995 by Wiles [1] . To achieve his proof, Wiles had to deploy “sophisticated” tools and difficult to access for the non-specialist [2] [7] . Even partial results like Abel’s conjecture and the cases where
or even
in Fermat’s equation have not been fully resolved [6] . Indeed, the second case,
with
a prime, of these subproblems still awaits direct proof. Thus, the search for new ways that are accessible and comprehensible to most amateurs is still ongoing [8] [9] [10] .
In 2021, Serdar Beji has numerically calculated solutions of a generalized form of Fermat’s equation as a function of the number of terms and the degree of this equation [11] :
(2)
This previous Diophantine equation, under certain conditions, does not admit solutions. Nevertheless, it should be noted that for
(3)
Scheinman L. J. found several non-trivial solutions based on relations between some known solutions or their elements [12] . He presented two different methods for calculating some solutions of Equation (3) [12] .
Let
be the set of proven or hypothetical non-trivial solutions of the Pythagoras-Fermat equation, the objective of this paper is to prove the following two main results.
Theorem 1. Let
be an integer,
such that
,
and
be its respective Diophantine quotients and remainders. We have:
.
Theorem 2. Let
an integer,
such that
,
and
be its respective Diophantine quotients and remainders. We have:
.
We apply these theorems to prove following result.
Theorem 3. Let
an integer,
such that
,
and
be its respective Diophantine quotients and remainders. We have:
.
When
, Theorem 3 directly proves that FLT is true in the case where
and
.
To which must be added this important result:
Theorem 4. Let
a prime
such that
,
and
be its respective Diophantine quotients and remainders. We have:
and
or
and
.
2. Preliminaries
Definition 2.1 Let
be an integer, we call the subset of
defined as follows,
Pythagoras’-Fermat’s domain.
The set
represents the set of non-trivial triplet solutions of the Pythagoras’ or Fermat’s equation. The Fermat-Wiles theorem shows that if
then
. In our study, we assume that a priori this set contains possible solutions.
Lemma 2.1. Let
be an integer,
an integer triplet such that
. We have.
Proof.
Let us prove by the absurd by assuming that
and
.
where
and
because
because
where the symbol
designates the logic empty clause. It means absurd. So
.
Lemma 2.2. Let
be an integer,
an integer triplet such that
. So, there are unique pairs of natural numbers (
) and (
) such that:
.
Proof. Let
, according to Lemma 2.1. and the division theorem, we have:
Remark 2.1. (
) and (
) are unique. If
then
and
. Because, for example
as a result
because of lemma 2.1.
Definition 2.2. The pair of unique integer numbers (
) and (
) appearing in Lemma 2.1 define the Diophantine quotient (
) and the Diophantine remainders (
) of triplet solution
of the Pythagoras’-Fermat’s equation. When
, the triplet solution is a Pythagorean triplet and (
), (
) are calls Pythagorean quotients and remainders of this solution.
The Definition 2.2 relies on the division theorem or algorithm ( [3] , p.334).
Lemma 2.3. Let
be an integer and
an integer triplet such as
. We have
Proof.
Remark 2.2. We have
otherwise
which implies
, which is absurd.
Lemma 2.4. Let
be an integer,
such that
. We have:
.
Proof.
Remark 2.3: This property is also found in ( [4] , p. 100).
Lemma 2.5. Let
be an integer,
such that
,
and
be its Diophantine quotients. We have:
.
Proof
On the one hand,
is an increasingly ordered triplet so
. Moreover, this triplet is a solution of Pythagoras’-Fermat’s equation, so by lemma 2.1
. We can therefore apply the division algorithm. There are therefore unique pairs of integers
and
such that
and
such that
.
On the other hand,
Hence
Remark 2.3. Note that
and
are non-zero. Otherwise, b or c would be less than a.
The following lemma is important for what follows. It will be used as a basis for the proof of the two theorems.
Lemma 2.6. Let
be an integer,
such that
and
and
, its Diophantine quotients and remainders associates. We have:
Proof. We know that:
. According to lemmas 2.4 and 2.5, we have
Proposition 2.1. Let
be an integer,
such that
and
and
be its Diophantine quotients and remainders associates. We have
.
Proof. By absurd suppose that
. According to lemma 2.6
because
Lemma 2.7. Let
be an integer,
such that
. We have:
and
.
Lemma 2.8. Let
be an integer,
such that
. We have:
and
.
Lemma 2.9. Let
be an integer,
such that
. We have:
.
Proof. According to Euclid algorithm, we have,
Lemma 2.10. Let
be an integer,
such that
. We have:
.
Proof. Let
and
. We have on the one hand.
because
and
Hence
.
On the other hand,
because
and
Hence
.
Proposition 2.2. Let
be an integer,
such that
. We have:
is a primitive triplet.
3. Proof of Theorems
In this section, we prove Theorems 1 and 2 stated in our introduction.
3.1. Proof of Theorem 1
To prove Theorem 1, we proceed by implication.
Proof. Let
an integer and
. On the one hand, let’s prove that: if
then
. We have:
Reciprocally
3.2. Proof of Theorem 2
We use the same approach as before to prove Theorem 2.
Proof. Let
be an integer and
. On the one hand,
On the other hand, we prove the reciprocal of the previous result.
Proposition 3.1. Let
be an integer,
such that
and
its Diophantine quotients. Then
Proof. Let
On the one hand, according to Theorem 1, we have
On the other hand, according to Theorem 2, we have
Hence the result.
Example 3.1. Table 1 illustrates the values of Diophantine quotients and remainders in the case of the Pythagorean equation. This table, obtained by the python program calculates the Diophantine quotients and remainders of some Pythagorean triplets. The algorithm of the program in Figure 1 is based on the Definition 2.2
Table 1. Examples of Diophantine quotients and remainders of some Pythagorean triplets.
Remark 3.1. The data in Table 1 were extracted from the results of the Calc_pythaQ_R(5, 39) and Calc_pythaQ_R(287, 300) commands. The first three columns identify a Pythagorean triplet, columns 4 and 5 respectively identify the Diophantine quotients
and
(note that either
or
) the last two columns identify
and
. They confirm the results of Theorems 1 and 2 as well as that of Proposition 3.2.
Figure 1. Python program to compute Pythagorean triples and their Diophantine quotients and remainders.
4. Applications
We apply the previous results to prove theorems 3 and 4. Theorem 3 gives a partial proof of FLT and gives new properties of Pythagorean triplets when Equation (1) becomes:
(4)
Let us denote by
the set of hypothetical solution of the Equation (4). According to Proposition 3.1, we can write
with
and
where
is the integer part function.
Remark 4.1.
and
.
We have, the following result.
Proposition 4.1. Let
an integer and
as previously defined. We have:
Proof. We proceed by absurd, supposing that
. So, we have:
according to Lemma 2.7.
according to Lemma 2.8
Hence the result.
Proof of Theorem 3. Theorem 3 is an immediate consequence of Proposition 4.1.
Remark 4.2. When
, the following Python program calculates Pythagorean triplets that verify whether Theorem 3. The program also tests this proposition.
Indeed, the program of Figure 2 calculates respectively the number of Pythagorean triplets such that
and (
and
). Then, it compares these two numbers to check the theorem 3: if there is equality the theorem 3 is checked otherwise it is not. This program also computes Pythagorean triplets
such that
and it’s Pythagorean quotients and remainders. The results in Table 2 show that the theorem 3 is verified for the range of Pythagorean triplets tested.
The OK in the last row of Table 2 means that in the defined range, the Pythagorean triples such that
are of the same number as the triplets satisfying
and
.
Figure 2. Python program compute Pythagorean triplets such as
or
and verify theorem 3.
Table 2. Result of very_theo3(3, 16) showing that theorem 3 is true for Pythagorean triplets
where
.
Proof of Theorem 4.
On the one hand, suppose that
and
. We have
and
because of Theorem 1
Hence
and
On the other hand, suppose that
and
. We have
and
because of Theorem 2
Hence
and
.
Remark. When n = 2, theorem 4 becomes the Pythagorean Quotients and Remainders Theorem (PQR Theorem). In this case, the Quotients and Remainders are said Pythagorean and we can compute them (see Table 1).
5. Conclusions
In this paper we have shown that if
is a solution of the Fermat equation and
and
are its Diophantine quotients and remainders, then
if and only if
and
if and only if
. These new properties used efficiently allowed us to find new properties verified by the Pythagorean triplets and to prove algebraically an important partial result of the FLT. This study opens new perspectives in the study of Diophantine equations and their applications. Here are some issues that can arise: Let
be a solution of Pythagoras’-Fermat’s equation with
and
its Diophantine quotients and remainders:
1) In the case of Pythagorean triplets, we must solve the following questions.
a)
is it increased or not (study the evolution of
)?
b) Which is new expression of
when
?
c) New classification of
use Diophantine quotients and remainders properties and possible cryptographic applications.
2) In the case of FLT being false, we have the following conjectures:
a) If
is a prime and
then
with e is Fermat principal divisor of b [10] .
b) If
is a prime then p is bounded (
).
c) If
is a prime then
and
or 2.
3) Generalize Diophantine quotients and remainders to variants of Fermat’s equation such as Equations (2) and (3).