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Logical equality is a logical operator that compares two truth values, or more generally, two formulas, such that it gives the value True if both arguments have the same truth value, and False if they are different.
In logic and mathematics, statements and are said to be logically equivalent if they have the same truth value in every model. [1] The logical equivalence of and is sometimes expressed as , ::, , or , depending on the notation being used.
Define e x as the value of the infinite series = =! = + +! +! +! + (Here n! denotes the factorial of n. One proof that e is irrational uses a special case of this formula.) Inverse of logarithm integral.
The assertion that Q is necessary for P is colloquially equivalent to "P cannot be true unless Q is true" or "if Q is false, then P is false". [9] [1] By contraposition, this is the same thing as "whenever P is true, so is Q". The logical relation between P and Q is expressed as "if P, then Q" and denoted "P ⇒ Q" (P implies Q).
𝐩 𝐪 𝐫 𝐬 𝐭 𝐮 𝐯 U+1D43x 𝐰 𝐱 𝐲 𝐳 𝐴 𝐵 𝐶 𝐷 𝐸 𝐹 𝐺 𝐻 𝐼 𝐽 𝐾 𝐿 U+1D44x 𝑀 𝑁 𝑂 𝑃 𝑄 𝑅 𝑆 𝑇 𝑈 𝑉 𝑊 𝑋 𝑌 𝑍 𝑎 𝑏 U+1D45x 𝑐 𝑑 𝑒 𝑓 𝑔 𝑖 𝑗 𝑘 𝑙 𝑚 𝑛 𝑜 𝑝 𝑞 𝑟 U+1D46x 𝑠 𝑡 𝑢 𝑣 𝑤 𝑥 𝑦 𝑧 𝑨
For any poset P there is a complete Boolean algebra B and a map e from P to B + (the non-zero elements of B) such that the image is dense, e(p)≤e(q) whenever p≤q, and e(p)e(q)=0 whenever p and q are incompatible. This Boolean algebra is unique up to isomorphism.
r = | z | = √ x 2 + y 2 is the magnitude of z and; φ = arg z = atan2(y, x). φ is the argument of z, i.e., the angle between the x axis and the vector z measured counterclockwise in radians, which is defined up to addition of 2π. Many texts write φ = tan −1 y / x instead of φ = atan2(y, x), but the first equation needs ...
A binary equaliser (that is, an equaliser of just two functions) is also called a difference kernel.This may also be denoted DiffKer(f, g), Ker(f, g), or Ker(f − g).The last notation shows where this terminology comes from, and why it is most common in the context of abstract algebra: The difference kernel of f and g is simply the kernel of the difference f − g.