Trivalue Oddagon Type 1
Places a candidate, finds the contradiction it causes, and removes it.
All candidates have been entered in the empty cells.
Call the three digits 3, 5 and 7 α, β and γ in any order, and suppose all 12 cells use only them. Without loss of generality: cell A=α, cell C=β, cell E=γ. cell A=α leave β or γ for cell B.
If cell B=β cell E=γ, cell B=β force cell F=α. cell C=β, cell F=α force cell D=γ. cell E=γ leave α or β for cell G.
If cell B=β and cell G=α cell B=β, cell G=α force cell H=γ. cell C=β, cell G=α force cell I=γ. cell A=α, cell I=γ force cell K=β. cell F=α, cell H=γ, cell K=β leave no α, β or γ for cell L.
If cell B=β and cell G=β cell A=α, cell G=β force cell K=γ. cell C=β, cell K=γ force cell I=α. cell D=γ, cell I=α force cell J=β. cell F=α, cell K=γ, cell J=β leave no α, β or γ for cell L.
If cell B=γ cell C=β, cell B=γ force cell D=α. cell E=γ, cell D=α force cell F=β. cell E=γ leave α or β for cell G.
If cell B=γ and cell G=α cell B=γ, cell G=α force cell H=β. cell C=β, cell G=α force cell I=γ. cell D=α, cell H=β, cell I=γ leave no α, β or γ for cell J.
If cell B=γ and cell G=β cell B=γ, cell G=β force cell H=α. cell A=α, cell G=β force cell K=γ. cell F=β, cell H=α, cell K=γ leave no α, β or γ for cell L.
Every case contradicts the rules. Only cell J can take a different digit, so it cannot take 3, 5 and 7. Candidates 3, 5 and 7 marked × can be removed.