/- Copyright 2026 The Formal Conjectures Authors. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. -/ import FormalConjecturesUtil

Dubner's conjecture

Reference: Every even number greater than 4208 is the sum of two t-primes by Harvey Dubner.

namespace DubnerConjecture

A twin prime is a prime number that has a prime gap of 2, meaning either p - 2 or p + 2 is also prime.

def IsTwinPrime (p : ) : Prop := p.Prime ((p - 2).Prime (p + 2).Prime) @[category test, AMS 11] theorem t1 : ¬IsTwinPrime 2 := ¬IsTwinPrime 2 All goals completed! 🐙 @[category test, AMS 11] theorem t2 : IsTwinPrime 3 := IsTwinPrime 3 All goals completed! 🐙 @[category test, AMS 11] theorem t3 : IsTwinPrime 5 := IsTwinPrime 5 All goals completed! 🐙 @[category test, AMS 11] theorem t4 : IsTwinPrime 101 := IsTwinPrime 101 All goals completed! 🐙 @[category test, AMS 11] theorem t5 : ¬IsTwinPrime 100 := ¬IsTwinPrime 100 All goals completed! 🐙

Every even number greater than 4208 is the sum of two twin primes.

@[category research open, AMS 11] theorem declaration uses 'sorry'dubner_conjecture (n : ) (hn : 4208 < n) (h : Even n) : p q : , IsTwinPrime p IsTwinPrime q p + q = n := n:hn:4208 < nh:Even n p q, IsTwinPrime p IsTwinPrime q p + q = n All goals completed! 🐙 end DubnerConjecture