How to find a logical statement equivalent to the one I have?

  • Thread starter omoplata
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Longleftrightarrow ( D \wedge C )In summary, there is a Wikipedia table of valid argument forms in propositional logic that can be used to find equivalent logical statements without having to draw truth tables. One possible equivalent statement to (A \wedge B) \Longleftrightarrow (A \wedge C) is ( A \wedge ( B \leftrightarrow C ) ) \Longleftrightarrow ( D \wedge C ).
  • #1
omoplata
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I have the following logical statement
[tex](A \wedge B) \Longleftrightarrow (A \wedge C)[/tex]
I want to find other logical statements that are equivalent to this. But I don't want to draw truth tables.

Is there a list of 'theorems' that I can look up somewhere? For example, if I have an equivalent statement for [itex]D \Longleftrightarrow (A \wedge C)[/itex], then I can maybe substitute [itex]D = (A \wedge B)[/itex] and maybe come up with something.

Sorry if my terminology is wrong. Logic is not exactly my subject.
 
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  • #3
That helps. Thanks.
 
  • #4
I am pretty sure that this is equivalent:
( A [itex]\wedge[/itex] ( B [itex]\leftrightarrow[/itex] C ) )
 
  • #5


There are several ways to find logical statements that are equivalent to the one you have. One approach is to use logical equivalences, which are rules that allow you to manipulate logical statements while preserving their truth value. These rules can be found in any introductory logic textbook or online resource.

For example, one logical equivalence that is relevant to your statement is the distributive law, which states that (A \wedge B) \Longleftrightarrow (A \wedge C) is equivalent to A \wedge (B \Longleftrightarrow C). So, you could substitute D = (B \Longleftrightarrow C) and get D \Longleftrightarrow A \wedge D, which is equivalent to your original statement.

Another approach is to use logical inference rules, such as modus ponens or modus tollens, to derive equivalent statements. These rules allow you to make deductions based on the logical structure of a statement. For example, if you have the statement A \rightarrow B and you know that A is true, you can infer that B is also true. Using these rules, you can manipulate your original statement to derive equivalent statements without having to draw truth tables.

In terms of finding a list of theorems, there are many resources available online that provide lists of logical equivalences and inference rules. Some examples include the Stanford Encyclopedia of Philosophy, the Internet Encyclopedia of Philosophy, and various logic textbooks. It may also be helpful to consult with a logic expert or take a logic course to gain a deeper understanding of logical equivalences and how to use them effectively.
 

1. How do I determine if two statements are logically equivalent?

To determine if two statements are logically equivalent, you can use a truth table. Write out all the possible combinations of truth values for the variables in both statements and compare the resulting truth values for each combination. If the truth values are the same, then the statements are logically equivalent.

2. Can I use logical equivalences to simplify complex statements?

Yes, you can use logical equivalences to simplify complex statements. By identifying equivalent statements, you can replace parts of a statement with simpler expressions, making it easier to understand and work with.

3. How can I prove that two statements are logically equivalent?

You can prove that two statements are logically equivalent by using logical equivalences or by using a proof method such as direct proof, proof by contradiction, or proof by contrapositive. These methods involve breaking down the statements and showing that they are equivalent through a series of logical steps.

4. Is there a way to check for logical equivalence without using a truth table?

Yes, there are other ways to check for logical equivalence without using a truth table. You can use logical equivalences, as mentioned before, or you can use a logic calculator or software that can evaluate and compare the truth values of two statements.

5. Can two statements be logically equivalent but have different grammatical structures?

Yes, two statements can be logically equivalent but have different grammatical structures. Logical equivalence is based on the truth values of the statements, so as long as the truth values are the same, the statements are considered equivalent. This means that the grammatical structure or wording of the statements can differ, but they still convey the same logical meaning.

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