๐งฉ Can Modulus 9 Appear Exactly Twice in an Odd Covering System?
A computer-assisted mathematical proof rules out an entire finite covering-system class.
๐ข A surprisingly specific question
In number theory, a covering system is a finite collection of congruences whose residue classes together cover every integer.
Here, the modulus is the repeating step size of a congruence class.
For example, each congruence has the form
x == a_i (mod m_i)
Now impose three conditions:
- every modulus is odd and greater than
1; - modulus
9appears exactly twice; - every other modulus appears at most once.
A natural question is:
Can such a covering system exist?
The answer is:
No.
That is the central result of Shunyaya Residual Capacity Theory (SRCT), presented as a computer-assisted mathematical proof.
The theorem is class-wide: it does not eliminate a few examples or a bounded search region. It rules out every finite covering system satisfying those exact conditions.
๐ Explore the complete SRCT repository on GitHub
๐งฉ Why modulus 9 matters
A standard quantity in this area is t_9: the least number of times modulus 9 must occur in a covering system whose remaining moduli are odd, distinct, and greater than 1.
Published constructions give
t_9 <= 3
SRCT proves
t_9 != 2
So the remaining possibilities are
t_9 in {0,1,3}
That distinction matters.
SRCT does not prove t_9 = 3.
The cases where modulus 9 occurs zero times or once remain outside this theorem.
What has been eliminated is the entire exact-two case.
๐ The difficult part: going from finite computation to a universal statement
A computer can exhaust a finite state space.
But the theorem concerns arbitrary finite covering systems, whose least common multiple may contain additional primes or higher prime powers.
So a finite search alone is not enough.
SRCT uses the finite modulus
K = 11486475 = 3^3 * 5^2 * 7 * 11 * 13 * 17
as an obstruction core.
Importantly,
K is not an assumed upper bound on the LCM.
Instead, the proof establishes a mathematical bridge showing that additional prime support and higher prime-power depth cannot escape the obstruction detected at the finite core.
In simplified form:
finite exact obstruction + universal extension argument -> class-wide nonexistence
That bridge is what turns the finite computation into a theorem about every finite covering system satisfying the three conditions above.
๐งฎ What the computer actually does
The proof separates two responsibilities.
The mathematical layer establishes the reductions, projection principles, lifting arguments, residual-deficit transport, p-adic layer behavior, non-erosion inequalities, and the final contradiction.
The computational layer verifies the finite obstruction using exact integer and rational arithmetic.
Among the frozen finite landmarks are:
45unordered placements of the two modulus-9 residues896balanced q45 states19712direct q63 continuations3030hard late-parent groups138448hard engaged edges0nonpositive q99 terminal bundles
No floating-point approximation is needed for the theorem-critical finite calculations.
โ Reproducibility is part of the result
The repository was built so that the theorem-supporting computation can be checked rather than simply trusted.
Current verification endpoints include:
556/556 PASSโโโrepository self-test
565/565 PASSโโโstandard theorem binding
335105/335105 PASSโโโstrengthened adversarial proof audit
The repository also contains 114 scientific files whose exact identities are cryptographically bound, including the theorem manuscripts, theorem-binding objects, and a byte-preserved 102-object predecessor chain.
The verification system checks issues such as:
quantifier_gap:NONE
domain_escape:NONE
inequality_direction_failure:NONE
finite_interface_mismatch:NONE
circular_dependency:NONE
scope_overclaim:NONE
These checks do not replace the mathematics.
They help verify that the mathematical argument, finite evidence, and computational interfaces remain consistently bound together.
โ๏ธ What isโโโand is notโโโbeing claimed
The result is intentionally narrow.
SRCT establishes:
No finite odd covering system exists with modulus 9 occurring exactly twice while every other modulus occurs at most once.
It does not establish:
- impossibility when modulus
9occurs zero times; - impossibility when modulus
9occurs once; t_9 = 3;- formal verification in a proof assistant;
- absolute bibliographic priority.
The universal mathematical lemmas have not been formally verified in a proof assistant. The result is therefore presented as a computer-assisted mathematical proof, supported by exact computation, reproducible verification, and strengthened consistency audits.
๐ Why This Result Is Interesting
The most interesting part is not simply that a large computation returned โno.โ
The deeper structure is:
a finite obstruction can survive arbitrary finite enlargement when the proof establishes the right transport and non-erosion principles.
That changes the role of computation.
Instead of asking the machine to somehow inspect an unbounded family of finite cases, the proof identifies a finite obstruction and then proves mathematically that additional prime support or higher prime-power depth cannot repair it.
In compact form:
universal proof + exact finite obstruction + reproducible theorem binding
-> class-wide modulus-9 exact-two nonexistence
๐ Explore the full proof
The GitHub repository contains the normative theorem manuscript, exact computational evidence, frozen scientific chain, theorem dependency map, reproducibility records, verification tools, SHA-256 scientific identities, proof-audit certificates, and automated verification workflow.
๐ Shunyaya Residual Capacity Theory on GitHub
The repository is the right place for the complete mathematical argument and technical details.
๐ The larger question
A simple-looking question started the journey:
Can modulus 9 occur exactly twice?
For this entire class of finite odd covering systems, the answer is now:
No.
What remains is just as interesting:
t_9 in {0,1,3}
And that leaves the deeper unresolved cases still open.
One exact multiplicity is gone. The surrounding number-theoretic landscape remains.
OMP