Math


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☆★   ☚ ☛ ☜ ☝ ☞☟    ⚓ ⚠☠ ☢ ⚙⚖ ☪ ☫ ☭ ⚑⚐ ☮   ☹ ☺ ☻ here

Greek Alphabets

 alpha  beta  gamma  delta  epsilon  zeta  eta  theta  iota  kappa  lambda  mu  nu  xi  omicron  pi  rho  sigma  tau  upsilon  phi  chi  psi  omega
 Α  Β  Γ  Δ  Ε  Ζ  Η  Θ  Ι  Κ  Λ  Μ  Ν  Ξ  Ο  Π  Ρ  Σ  Τ  Υ  Φ  Χ  Ψ  Ω
 α  β  γ  δ  ε  ζ  η  θ  ι  κ  λ  μ  ν  ξ  ο  π  ρ  σ (ς)  τ  υ  φ  χ  ψ  ω

Other Mathematical Symbols

 nabla symbol  ∂ Partial Derivative
 Congruence  Modulo n
  Equality  Multiplication
  Therefore  Because Implication

Equivalence
  Maps  Logical Negation
  AND OR
XOR
  Qualifiers Sets  Infinity
 ∇  ∂  a ≡ b (mod n)  ≠ ≤  ≥ ± ≈ ≜(defined
to be)
∝(proportional to)
 		 × ÷ √ ∛∜
∏(product)
  ∴
  ∵  ⇒  →  ⊃

 ⇔  ↔  ↕ ↑↓←↟		  ↦  ¬  ~
 ∧∨ ⊕  ∀∃ ∄
  ∅∈  ∉   ⊆  ⊂  ⊇  ⊃ ∪∩  ∖
  ∞
   Derived from greek word delta often read as "der", "del", "dow", "die", "dava", "partial", "round d", "curly d" or simply "d"
 x+1=6    
∴ x=5
                     

 Floor
Ceiling
  integral  Orthogonal  Entailment

Inference
  Section Markers
  Hats or Superscripts,
etc
 ⌊…⌋
⌈…⌉
  ∫ ∮ 
 ⊥ ∟  ⊧ 
 ⊢
  § ▲ ▼ ■ † ‡ •○ ♦ ◊   ° (degree)
⁀ (hat)
a²ⁿ ½ ¼ ¡¿
       A ⊧ B means the sentence A entails the sentence B, that is in every model in which A is true, B is also true.

x ⊢ y means y is derivable from x.
   e

For a more comprehensive list please refer to   wikipedia List of mathematical symbols     chexed.com/.../asciicodes.php wikipedia signs  http://www.fileformat.info/info/unicode/block/mathematical_operators/images.htm






A necessary condition of a statement must be satisfied for the statement to be true. In formal terms, a statement N is a necessary condition of a statement S if S implies N (S ⇒ N).

A sufficient condition is one that, if satisfied, assures the statement's truth. In formal terms, a statement S is a sufficient condition of a statement N if S implies N (S ⇒ N).


Closed-form expression: If the expression can be expressed analytically in terms of a bounded number of certain "well-known" functions. Typically, these well-known functions are defined to be elementary functions—constants, one variable x, elementary operations of arithmetic (+ − × ÷), nth roots, exponent and logarithm (which thus also include trigonometric functions and inverse trigonometric functions).

Ring

It consists of a set together with two binary operations usually called addition and multiplication, which satisfy the following set of axioms: the addition is associative and commutative, has an identity and each element in the set has an additive inverse; the multiplication is associative, is not necessarily commutative, has an identitya and distributes over addition.

Field

A ring whose nonzero elements form a commutative group under multiplication

Hilbert Space

Generalizes the notion of Euclidean space. It extends the methods of vector algebra and calculus from the two-dimensional Euclidean plane and three-dimensional space to spaces with any finite or infinite number of dimensions. A Hilbert space is an abstract vector space possessing the structure of an inner product that allows length and angle to be measured.

Complete Space (Cauchy Space)



Orthonormal Basis
A subset {v1,...,vk} of a vector space V, with the inner product <,>, is called orthonormal if <vi,vj>=0 when i≠j. That is, the vectors are mutually perpendicular. Moreover, they are all required to have length one: <vi,vi>=1.




General Notes

Logistic Function or Sigmoid Function:  1/(1+e^(-t))

in relation to population growth. It can model the "S-shaped" curve of growth of some population P. The initial stage of growth is approximately exponential; then, as saturation begins, the growth slows, and at maturity, growth stops.
- the rate of reproduction is proportional to both the existing population and the amount of available resources, all else being equal.
- to describe the self-limiting growth of a biological population.


up to
"all other things being equal"
It indicates that its grammatical object is some equivalence class, to be regarded as a single entity, or disregarded as a single entity. If this object is a class of transformations (such as "isomorphism" or "permutation"), it implies the equivalence of objects one of which is the image of the other under such a transformation.
e.g. up to isomorphism
"there are seven reflecting tetrominos, up to rotations", which makes reference to the seven possible contiguous arrangements of tetrominoes (collections of four unit squares arranged to connect on at least one side) which are frequently thought of as the seven Tetris pieces (box, I, L, J, T, S, Z.) This could also be written "there are five tetrominos, up to reflections and rotations", which would take account of the perspective that L and J could be thought of as the same piece, reflected, as well as that S and Z could be seen as the same.


Morphism
Any structure-preserving mappings between two mathematical structures.
Homomorphism
a general morphism is called homomorphism. A structure-preserving map between two algebraic structures. The word homomorphism meaning "same" + "shape". Isomorphisms, automorphisms, and endomorphisms are all types of homomorphism.

EXAMPLE 1
The real numbers are a ring, having both addition and multiplication. The set of all 2 × 2 matrices is also a ring, under matrix addition and matrix multiplication. If we define a function between these rings as follows:
where r is a real number. Then ƒ is a homomorphism of rings, since ƒ preserves both addition:

and multiplication:

EXAMPLE 2

For another example, the nonzero complex numbers form a group under the operation of multiplication, as do the nonzero real numbers. (Zero must be excluded from both groups since it does not have a multiplicative inverse, which is required for elements of a group.) Define a function ƒ from the nonzero complex numbers to the nonzero real numbers by

f(z) = |z|, That is, ƒ(z) is the absolute value (or modulus) of the complex number z. Then ƒ is a homomorphism of groups, since it preserves multiplication:

Note that ƒ cannot be extended to a homomorphism of rings (from the complex numbers to the real numbers), since it does not preserve addition:






Automorphism: symmetry - map obj to itself.
An automorphism of a set X is an arbitrary permutation of the elements of X
The set of integers, Z has a unique nontrivial automorphism: negation.
Endomorphism: An invertible endomorphism of X is called an automorphism [so endomorphism is a one way automorphism???!!!]. an automorphism is an endomorphism (i.e. a morphism from an object to itself) which is also an isomorphism
from the Greek adverb endon ("inside") and morphosis ("to form" or "to shape").
Isomorphism
meaning "equal," and morphosis, meaning "to form" or "to shape."
A map that preserves sets and relations among elements.
an isomorphism is a morphism f: X → Y in a category for which there exists an "inverse" f −1: Y → X, with the property that both f −1f = idX and f f −1 = idY.[3]

EXAMPLE
Consider the group (Z6, +), the integers from 0 to 5 with addition modulo 6. Also consider the group (Z2 × Z3, +), the ordered pairs where the x coordinates can be 0 or 1, and the y coordinates can be 0, 1, or 2, where addition in the x-coordinate is modulo 2 and addition in the y-coordinate is modulo 3. These structures are isomorphic under addition, if you identify them using the following scheme:
(0,0) → 0
(1,1) → 1
(0,2) → 2
(1,0) → 3
(0,1) → 4
(1,2) → 5
or in general (a,b) → (3a + 4b) mod 6. For example note that (1,1) + (1,0) = (0,1), which translates in the other system as 1 + 3 = 4. Even though these two groups "look" different in that the sets contain different elements, they are indeed isomorphic: their structures are exactly the same.

Hence: isomorphism is to realize that two groups are structurally the same even though the names and notation for the elements are different. We say that groups G and H are isomorphic if there is an isomorphism between them. Another way to think of an isomorphism is as a renaming of elements.
For example, the set of complex numbers {1, i, -i, -1} under complex multiplication, the set of integers {0, 1, 2, 3} under addition modulo 4, and the subgroup {1, (1 2 3 4), (1 3)(2 4), (1 4 3 2)} of S4  look different but are structurally the same. They are all of order 4 (but that's not what makes them isomorphic) and are cyclic groups. The maps i ↦ 1 (for the first pair of groups) and 1 ↦ (1 2 3 4) (for the second and third of the groups) provide the necessary isomorphisms.