'********** multiple variables introduction 'Lock-1 can be opened by every key. <<$x --> key> ==> <{lock1} --> (/,open,$x,_)>>. 'Lock-1 is a lock. <{lock1} --> lock>. 166 'There is a lock that can be opened by every key. ''outputMustContain('(&&,<#1 --> lock>,<<$2 --> key> ==> <#1 --> (/,open,$2,_)>>). %1.00;0.81%') 'I guess every lock can be opened by every key. ''outputMustContain('<(&&,<$1 --> key>,<$2 --> lock>) ==> <$2 --> (/,open,$1,_)>>. %1.00;0.45%')