Either/Or Clues in Logic Grid Puzzles

Part 2 of 5 of How to Solve Logic Grid Puzzles.

An either/or clue names one item and gives two options for it. Exactly one option is true, and the other is false.

Clue 2. The bear was either the white animal or the gold animal.

Cross out everything else

Both options are colors. Whichever one is true, the bear was not any other color, so cross out orange and red in the bear column.

Rule out one option and the other is true

From clue 3, the turtle was white, so the bear's white square already holds an X. That rules out the first option, which makes the second one true: the bear was gold.

The grid shows the same thing. The bear column had three X's, so its last square had to be the circle.

When the options are in different categories

Some either/or clues mix two categories, such as "The dog was either the $3 animal or the red animal". There is no row of other options to cross out this time, but the clue holds a hidden fact instead.

Exactly one option is true, so the $3 animal and the red animal can't be the same animal. If they were, the two options would be true together or false together. So put an X where $3 meets red. You can do that before you know anything about the dog, which makes it an easy X to miss.

After that, the clue works as before: rule out one option and the other is true.

Next: Greater than clues
Previous: True and false clues
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