I'm a bit confused regarding your proof for R(4,4). Supposing 3 strangers, they are strangers amongst themselves not strangers to A. All of those vertices are actually still friends with A under our initial assumption. I know R(4,4) is 18 but I'm not sure your proof is correct.
I'm a bit confused regarding your proof for R(4,4). Supposing 3 strangers, they are strangers amongst themselves not strangers to A. All of those vertices are actually still friends with A under our initial assumption. I know R(4,4) is 18 but I'm not sure your proof is correct.