<Tr> <Td> <Ul> <Li> Offer and acceptance </Li> <Li> Posting rule </Li> <Li> Mirror image rule </Li> <Li> Invitation to treat </Li> <Li> Firm offer </Li> <Li> Consideration </Li> <Li> Implication - in - fact </Li> <Li> Collateral contract </Li> </Ul> </Td> </Tr> <Ul> <Li> Offer and acceptance </Li> <Li> Posting rule </Li> <Li> Mirror image rule </Li> <Li> Invitation to treat </Li> <Li> Firm offer </Li> <Li> Consideration </Li> <Li> Implication - in - fact </Li> <Li> Collateral contract </Li> </Ul> <Li> Offer and acceptance </Li> <Li> Mirror image rule </Li>

​when the statute of frauds applies and there is no written proof of the contract the contract is