Every whale is a mammal.
Any whale is a mammal.
Whales are mammals.
If anything is a whale, it is a mammal.
Anything that is a whale is a mammal.
If anything is not a mammal, it is not a whale.
All non-mammals are non-whales.
A thing is a whale only if it is a mammal.
Only mammals are whales.
Nothing is a whale unless it is a mammal.
No whale is not a mammal.
NOTE: Seeing Minke whales swimming in the open sea quite close to our boat in Kennebunkport last summer was one of the highlights of the year. We had seen whales before in Cabo San Lucas, but only from the shore at a great distance. I would love to have also posted a link to Claire Hamill’s song You Take My Breath Away, but couldn’t find the original version from her Stage Door Johnnies record. Eva Cassidy had great success with her version, but Claire’s is really unforgettable. The "equivalents" list is excerpted from Logic by Wesley Salmon (Prentice-Hall, 1973).