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Which of the following are functions that are also one-to-one?
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{{CMD_143}}Mapping words to their meaning in a dictionary.{{CMD_144}}
{{CMD_145}}Given a runner racing forward on a straight path,
mapping time to the position of the runner.{{CMD_146}}
{{CMD_147}}Mapping people to their birth date.{{CMD_148}} {{CMD_149}}Mapping
mothers to their children.{{CMD_150}}
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{{CMD_152}}{{CMD_153}}
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{{CMD_155}} Since words may have more than one definition, ``relating
words to their definition in a dictionary'' is not a function.
{{CMD_156}} Since the runner is running forward on the straight path,
every time corresponds to a position, and every position
corresponds to a time. So this gives a one-to-one function.
{{CMD_157}} Since every person only has one birth date, ``relating
people to their birth date'' is a function. However, many people
have the same birth date, hence this function is not one-to-one.
{{CMD_158}} Since mothers can have more (or less) than one child,
``relating mothers to their children'' is not a function.
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