Primes and Bivariate Polynomials without Constant Terms: A Recursive Algorithm
K. Lakshmanan
TL;DR
This work tackles the problem of whether a bivariate polynomial $f(x,y)$ with non-negative coefficients and no constant term can take a prime value. It introduces a simple, constructive recursive obstruction based on gcd-divisibility patterns from substitutions, which is finite to verify up to $f(2,2)$ and yields a sufficient condition for non-primality. The main contribution is an algorithmic criterion that, if satisfied for all small input tuples, guarantees that $f(x,y)$ represents no primes; examples illustrate both prime-producing and prime-free cases, and the approach provides a perspective that can extend to multivariate and finite-field settings. The results complement classical conjectures like Bouniakowsky by offering a practical method to certify the absence of prime outputs in a broad class of bivariate polynomials and by pointing to several natural directions for future work and generalizations.
Abstract
We investigate the computational problem of determining whether a bivariate polynomial with non-negative coefficients and no constant term can attain a prime value. While classical conjectures such as Bouniakowsky's provide necessary conditions for univariate prime-representing polynomials, we introduce a new recursive algorithm that efficiently certifies when a bivariate polynomial form can produce no prime values at all. Our method is elementary and constructive, based on analyzing gcd-divisibility patterns arising from recursive substitutions into the polynomial. The obstruction criterion obtained leads to an efficient and elementary algorithm that certifies when a polynomial form cannot produce any prime values. The result is stronger than what is implied by the negation of Bouniakowsky's condition and applies to a wide class of polynomials, including transformations of univariate forms. We provide illustrative examples, analyze the complexity of the method, and discuss its connections to existing conjectures and possible generalizations.
