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Mathematics #235

Open anitsh opened 4 years ago

anitsh commented 4 years ago

Resources

Reference

285 Linear Alzebra

anitsh commented 4 years ago

Notes from book Mathematics for Computer Science by Eric Lehman, F Thomson Leighton and Albert R Meyer

A proof is a method of establishing truth Mathematics has its own specific notion of “proof.” A mathematical proof of a proposition is a chain of logical deductions leading to the proposition from a base set of axioms.

A proposition is a statement (communication) that is either true or false. For example, both of the following statements are propositions. The first is true, and the second is false. Proposition 1.1.1. 2 + 3 = 5. Proposition 1.1.2. 1 + 1 = 3.

A predicate can be understood as a proposition whose truth depends on the value of one or more variables. For example, we might use the name “P ” for predicate above: P .n/ WWD “n is a perfect square”; and repeat the remarks above by asserting that P .4/ is true, and P .5/ is false. This notation for predicates is confusingly similar to ordinary function notation. If P is a predicate, then P .n/ is either true or false, depending on the value of n. On the other hand, if p is an ordinary function, like n 2 C1, then p.n/ is a numerical quantity. Don’t confuse these two!

Propositions like these that are simply accepted as true are called axioms.

 Important true propositions are called theorems.  A lemma is a preliminary proposition useful for proving later propositions.  A corollary is a proposition that follows in just a few logical steps from a theorem.

The Well Ordering Principle Every nonempty set of nonnegative integers has a smallest element.