Function monomials_up_to_degree 

pub fn monomials_up_to_degree(num_vars: usize, degree: usize) -> Vec<Mono> 

All squarefree monomials of degree ≤ degree over num_vars ≤ 63 variables, ascending as u64s — enumerated directly (Gosper’s next-k-subset walk per degree class), never touching the 2ⁿ cube. This is the basis walk that lifts fixed-degree Nullstellensatz work past the clause engine’s 20-variable cap: the count is Σ_{k≤d} C(n,k) (nullstellensatz_basis_size), not 2ⁿ.