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Comments on Is concatenation a logical AND?

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Is concatenation a logical AND?

+4

−4

As a person with no significant background in mathematics and computer science I thought that concatenation and AND are logically identical if not very similar because both add something to something yet not by numerical addition (natural addition) so I found it sensical to say "x AND y" is weight to "x . y". But of course I might be wrong, so I ask:

Is concatenation (for example, as with . in PHP) a logical AND?

posted about 4 years ago

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General comments (7 comments)

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+3

−5

It is OR.

Assimilate FALSE to the empty string, and TRUE to any other string:

ε CONCATENATE ε = ε
ε CONCATENATE something = something
something CONCATENATE ε = something

What about both sides at TRUE:

something CONCATENATE something = somethingsomething

But because any non empty string assimilates as TRUE:

something CONCATENATE something = something

posted about 4 years ago

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Derek Elkins‭ wrote about 4 years ago

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You should clarify that for programming languages that will treat strings as boolean values and which interpret the empty string as false and all non-empty strings as true, then it will be the case that the boolean value associated to the concatenation will be the disjunction of the boolean value associated to the arguments. These assumptions are not true for PHP, e.g. "0" is false in PHP while "00" is true. These assumptions are also not true for many other languages.