Axiomatic System
 Undefined Terms
 Technical Terms : Definitions
  defined within these Undefined Terms
 Set of statements(Axioms)
  dealing with Undefined Terms and definitions
 All other Statements of the system- Theorems
  Logical consequences of these axioms.
Independent

  An axiom is said to be independent
 If it can not be logically deduced from the
 other axioms in the system.
Completeness

 A set of axioms is said to be complete
  If it is not possible to add any
 independent axiom on the system.
Consistency

 A set of axioms is said to be consistent
  If it is impossible to deduce a theorem
 (from axioms) that contradict any axiom
 or previously proved theorem.
Euclidean Geometry
 The Euclidean Geometry is an axiomatic system along with five axioms .

  The five axioms are:
  1. To draw a straight line from any point to any point.
  2. To produce [extend] a finite straight line continuously in a straight line.
  3. To describe a circle with any center and distance [radius].
  4. That all right angles are equal to one another.
  5. The parallel postulate: That, if a straight line falling on two straight lines
     make the interior angles on the same side less than two right angles, the
     two straight lines, if produced indefinitely, meet on that side on which are
     the angles less than the two right angles.

  It is possible to reject any or all of these and still have valid geometries with different
  principles. For example, if we simply toss out #5, we are no longer dealing with
  Euclidean Geometry, we are dealing with Hyperbolic geometry (in which there are
  infinite distinct lines parallel to another line through a given point)…. And if …
Geometry
Euclidean Geometry              Neutral Geometry        Non-Euclidean Geometry



                                                      there are infinite
                                                    distinct lines parallel
          Axiom:-5                                 through a given point

         there is unique line
                                 Common
          parallel through a
             given point
                                  Axioms
                                                   …… Axiom:-5
                                   1,2,3,4           there are no lines
                                                     parallel through a
                                                        given point
Four Point Geometry

Undefined Terms: Point, Line, On.
    Axiom 1: There exist exactly four distinct points.
    Axiom 2: Any two distinct points have exactly one line on both.
    Axiom 3: Each line is on exactly two points.


Def 1: Two lines on the same point are said to intersect
Def 2: Two lines that do not intersect are called parallel.

Theorem 1: Each point of the four-point geometry has exactly three lines on it
…
Are blue lines parallel?
Complete four point
                      Yes, see definition 2
Complete four point
                      Fano-Configuration

Geometry Introduction-c

  • 1.
    Axiomatic System  UndefinedTerms  Technical Terms : Definitions defined within these Undefined Terms  Set of statements(Axioms) dealing with Undefined Terms and definitions  All other Statements of the system- Theorems Logical consequences of these axioms.
  • 2.
    Independent Anaxiom is said to be independent If it can not be logically deduced from the other axioms in the system.
  • 3.
    Completeness A setof axioms is said to be complete If it is not possible to add any independent axiom on the system.
  • 4.
    Consistency A setof axioms is said to be consistent If it is impossible to deduce a theorem (from axioms) that contradict any axiom or previously proved theorem.
  • 5.
    Euclidean Geometry  TheEuclidean Geometry is an axiomatic system along with five axioms . The five axioms are: 1. To draw a straight line from any point to any point. 2. To produce [extend] a finite straight line continuously in a straight line. 3. To describe a circle with any center and distance [radius]. 4. That all right angles are equal to one another. 5. The parallel postulate: That, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles. It is possible to reject any or all of these and still have valid geometries with different principles. For example, if we simply toss out #5, we are no longer dealing with Euclidean Geometry, we are dealing with Hyperbolic geometry (in which there are infinite distinct lines parallel to another line through a given point)…. And if …
  • 6.
    Geometry Euclidean Geometry Neutral Geometry Non-Euclidean Geometry there are infinite distinct lines parallel Axiom:-5 through a given point there is unique line Common parallel through a given point Axioms …… Axiom:-5 1,2,3,4 there are no lines parallel through a given point
  • 7.
    Four Point Geometry UndefinedTerms: Point, Line, On. Axiom 1: There exist exactly four distinct points. Axiom 2: Any two distinct points have exactly one line on both. Axiom 3: Each line is on exactly two points. Def 1: Two lines on the same point are said to intersect Def 2: Two lines that do not intersect are called parallel. Theorem 1: Each point of the four-point geometry has exactly three lines on it …
  • 8.
    Are blue linesparallel? Complete four point Yes, see definition 2
  • 9.
    Complete four point Fano-Configuration