Some Puzzles about Cafe International: Answer 1

If no guests are at the bar, is it possible for
a seat at a table to be unfillable? If so, show
how; if not, prove it.
Answer
Yes. If two adjacent tables intersect in an empty
chair and one table has 2 women and one man and
the other table has 2 men and one woman, then the
empty chair cannot be filled because the first
table requires a man there, and the second table
requires a woman.
Jeff Goldsmith,
jeff@tintin.jpl.nasa.gov,
Jan. 4, 1999