Glossary of Principia Mathematica
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This is a list of the notation used in Alfred North Whitehead and Bertrand Russell's Principia Mathematica (1910–1913).
The second (but not the first) edition of Volume I has a list of notation used at the end.
Glossary[edit]
This is a glossary of some of the technical terms in Principia Mathematica that are no longer widely used or whose meaning has changed.
Symbols introduced in Principia Mathematica, Volume I[edit]
Symbol | Approximate meaning | Reference |
---|---|---|
✸ | Indicates that the following number is a reference to some proposition | |
α,β,γ,δ,λ,κ, μ | Classes | Chapter I page 5 |
f,g,θ,φ,χ,ψ | Variable functions (though θ is later redefined as the order type of the reals) | Chapter I page 5 |
a,b,c,w,x,y,z | Variables | Chapter I page 5 |
p,q,r | Variable propositions (though the meaning of p changes after section 40). | Chapter I page 5 |
P,Q,R,S,T,U | Relations | Chapter I page 5 |
. : :. :: | Dots used to indicate how expressions should be bracketed, and also used for logical "and". | Chapter I, Page 10 |
Indicates (roughly) that x is a bound variable used to define a function. Can also mean (roughly) "the set of x such that...". | Chapter I, page 15 | |
! | Indicates that a function preceding it is first order | Chapter II.V |
⊦ | Assertion: it is true that | *1(3) |
~ | Not | *1(5) |
∨ | Or | *1(6) |
⊃ | (A modification of Peano's symbol Ɔ.) Implies | *1.01 |
= | Equality | *1.01 |
Df | Definition | *1.01 |
Pp | Primitive proposition | *1.1 |
Dem. | Short for "Demonstration" | *2.01 |
. | Logical and | *3.01 |
p⊃q⊃r | p⊃q and q⊃r | *3.02 |
≡ | Is equivalent to | *4.01 |
p≡q≡r | p≡q and q≡r | *4.02 |
Hp | Short for "Hypothesis" | *5.71 |
(x) | For all x This may also be used with several variables as in 11.01. | *9 |
(∃x) | There exists an x such that. This may also be used with several variables as in 11.03. | *9, *10.01 |
≡x, ⊃x | The subscript x is an abbreviation meaning that the equivalence or implication holds for all x. This may also be used with several variables. | *10.02, *10.03, *11.05. |
= | x=y means x is identical with y in the sense that they have the same properties | *13.01 |
≠ | Not identical | *13.02 |
x=y=z | x=y and y=z | *13.3 |
℩ | This is an upside-down iota (unicode U+2129). ℩x means roughly "the unique x such that...." | *14 |
[] | The scope indicator for definite descriptions. | *14.01 |
E! | There exists a unique... | *14.02 |
ε | A Greek epsilon, abbreviating the Greek word ἐστί meaning "is". It is used to mean "is a member of" or "is a" | *20.02 and Chapter I page 26 |
Cls | Short for "Class". The 2-class of all classes | *20.03 |
, | Abbreviation used when several variables have the same property | *20.04, *20.05 |
~ε | Is not a member of | *20.06 |
Prop | Short for "Proposition" (usually the proposition that one is trying to prove). | Note before *2.17 |
Rel | The class of relations | *21.03 |
⊂ ⪽ | Is a subset of (with a dot for relations) | *22.01, *23.01 |
∩ ⩀ | Intersection (with a dot for relations). α∩β∩γ is defined to be (α∩β)∩γ and so on. | *22.02, *22.53, *23.02, *23.53 |
∪ ⨄ | Union (with a dot for relations) α∪β∪γ is defined to be (α∪β)∪γ and so on. | 22.03, *22.71, *23.03, *23.71 |
− ∸ | Complement of a class or difference of two classes (with a dot for relations) | *22.04, *22.05, *23.04, *23.05 |
V ⩒ | The universal class (with a dot for relations) | *24.01 |
Λ ⩑ | The null or empty class (with a dot for relations) | 24.02 |
∃! | The following class is non-empty | *24.03 |
‘ | R ‘ y means the unique x such that xRy | *30.01 |
Cnv | Short for converse. The converse relation between relations | *31.01 |
Ř | The converse of a relation R | *31.02 |
A relation such that if x is the set of all y such that | *32.01 | |
Similar to with the left and right arguments reversed | *32.02 | |
sg | Short for "sagitta" (Latin for arrow). The relation between and R. | *32.03 |
gs | Reversal of sg. The relation between and R. | 32.04 |
D | Domain of a relation (αDR means α is the domain of R). | *33.01 |
D | (Upside down D) Codomain of a relation | *33.02 |
C | (Initial letter of the word "campus", Latin for "field".) The field of a relation, the union of its domain and codomain | *32.03 |
F | The relation indicating that something is in the field of a relation | *32.04 |
The composition of two relations. Also used for the Sheffer stroke in *8 appendix A of the second edition. | *34.01 | |
R2, R3 | Rn is the composition of R with itself n times. | *34.02, *34.03 |
is the relation R with its domain restricted to α | *35.01 | |
is the relation R with its codomain restricted to α | *35.02 | |
Roughly a product of two sets, or rather the corresponding relation | *35.04 | |
⥏ | P⥏α means . The symbol is unicode U+294F | *36.01 |
“ | (Double open quotation marks.) R“α is the domain of a relation R restricted to a class α | *37.01 |
Rε | αRεβ means "α is the domain of R restricted to β" | *37.02 |
‘‘‘ | (Triple open quotation marks.) αR‘‘‘κ means "α is the domain of R restricted to some element of κ" | *37.04 |
E!! | Means roughly that a relation is a function when restricted to a certain class | *37.05 |
♀ | A generic symbol standing for any functional sign or relation | *38 |
” | Double closing quotation mark placed below a function of 2 variables changes it to a related class-valued function. | *38.03 |
p | The intersection of the classes in a class. (The meaning of p changes here: before section 40 p is a propositional variable.) | *40.01 |
s | The union of the classes in a class | *40.02 |
applies R to the left and S to the right of a relation | *43.01 | |
I | The equality relation | *50.01 |
J | The inequality relation | *50.02 |
ι | Greek iota. Takes a class x to the class whose only element is x. | *51.01 |
1 | The class of classes with one element | *52.01 |
0 | The class whose only element is the empty class. With a subscript r it is the class containing the empty relation. | *54.01, *56.03 |
2 | The class of classes with two elements. With a dot over it, it is the class of ordered pairs. With the subscript r it is the class of unequal ordered pairs. | *54.02, *56.01, *56.02 |
An ordered pair | *55.01 | |
Cl | Short for "class". The powerset relation | *60.01 |
Cl ex | The relation saying that one class is the set of non-empty classes of another | *60.02 |
Cls2, Cls3 | The class of classes, and the class of classes of classes | *60.03, *60.04 |
Rl | Same as Cl, but for relations rather than classes | *61.01, *61.02, *61.03, *61.04 |
ε | The membership relation | *62.01 |
t | The type of something, in other words the largest class containing it. t may also have further subscripts and superscripts. | *63.01, *64 |
t0 | The type of the members of something | *63.02 |
αx | the elements of α with the same type as x | *65.01 *65.03 |
α(x) | The elements of α with the type of the type of x. | *65.02 *65.04 |
→ | α→β is the class of relations such that the domain of any element is in α and the codomain is in β. | *70.01 |
sm | Short for "similar". The class of bijections between two classes | *73.01 |
sm | Similarity: the relation that two classes have a bijection between them | *73.02 |
PΔ | λPΔκ means that λ is a selection function for P restricted to κ | *80.01 |
excl | Refers to various classes being disjoint | *84 |
↧ | P↧x is the subrelation of P of ordered pairs in P whose second term is x. | *85.5 |
Rel Mult | The class of multipliable relations | *88.01 |
Cls2 Mult | The multipliable classes of classes | *88.02 |
Mult ax | The multiplicative axiom, a form of the axiom of choice | *88.03 |
R* | The transitive closure of the relation R | *90.01 |
Rst, Rts | Relations saying that one relation is a positive power of R times another | *91.01, *91.02 |
Pot | (Short for the Latin word "potentia" meaning power.) The positive powers of a relation | *91.03 |
Potid | ("Pot" for "potentia" + "id" for "identity".) The positive or zero powers of a relation | *91.04 |
Rpo | The union of the positive power of R | *91.05 |
B | Stands for "Begins". Something is in the domain but not the range of a relation | *93.01 |
min, max | used to mean that something is a minimal or maximal element of some class with respect to some relation | *93.02 *93.021 |
gen | The generations of a relation | *93.03 |
✸ | P✸Q is a relation corresponding to the operation of applying P to the left and Q to the right of a relation. This meaning is only used in *95 and the symbol is defined differently in *257. | *95.01 |
Dft | Temporary definition (followed by the section it is used in). | *95 footnote |
IR,JR | Certain subsets of the images of an element under repeatedly applying a function R. Only used in *96. | *96.01, *96.02 |
The class of ancestors and descendants of an element under a relation R | *97.01 |
Symbols introduced in Principia Mathematica, Volume II[edit]
Symbol | Approximate meaning | Reference |
---|---|---|
Nc | The cardinal number of a class | *100.01,*103.01 |
NC | The class of cardinal numbers | *100.02, *102.01, *103.02,*104.02 |
μ(1) | For a cardinal μ, this is the same cardinal in the next higher type. | *104.03 |
μ(1) | For a cardinal μ, this is the same cardinal in the next lower type. | *105.03 |
+ | The disjoint union of two classes | *110.01 |
+c | The sum of two cardinals | *110.02 |
Crp | Short for "correspondence". | *110.02 |
ς | (A Greek sigma used at the end of a word.) The series of segments of a series; essentially the completion of a totally ordered set | *212.01 |
Symbols introduced in Principia Mathematica, Volume III[edit]
Symbol | Approximate meaning | Reference |
---|---|---|
Bord | Abbreviation of "bene ordinata" (Latin for "well-ordered"), the class of well-founded relations | *250.01 |
Ω | The class of well ordered relations[2] | 250.02 |
See also[edit]
Notes[edit]
References[edit]
- Whitehead, Alfred North, and Bertrand Russell. Principia Mathematica, 3 vols, Cambridge University Press, 1910, 1912, and 1913. Second edition, 1925 (Vol. 1), 1927 (Vols. 2, 3).
External links[edit]
- List of notation in Principia Mathematica at the end of Volume I
- "The Notation in Principia Mathematica" by Bernard Linsky.
- Principia Mathematica online (University of Michigan Historical Math Collection):
- Proposition ✸54.43 in a more modern notation (Metamath)