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Definition df-trkg 25152
 Description: Define the class of Tarski geometries. A Tarski geometry is a set of points, equipped with a betweenness relation (denoting that a point lies on a line segment between two other points) and a congruence relation (denoting equality of line segment lengths). Here, we are using the following: for congruence, (𝑥 − 𝑦) = (𝑧 − 𝑤) where − = (dist‘𝑊) for betweenness, 𝑦 ∈ (𝑥𝐼𝑧), where 𝐼 = (Itv‘𝑊) With this definition, the axiom A2 is actually equivalent to the transitivity of addition, eqtrd 2644. Tarski originally had more axioms, but later reduced his list to 11: A1 A kind of reflexivity for the congruence relation (TarskiGC) A2 Transitivity for the congruence relation (TarskiGC) A3 Identity for the congruence relation (TarskiGC) A4 Axiom of segment construction (TarskiGCB) A5 5-segment axiom (TarskiGCB) A6 Identity for the betweenness relation (TarskiGB) A7 Axiom of Pasch (TarskiGB) A8 Lower dimension axiom (DimTarskiG≥‘2) A9 Upper dimension axiom (V ∖ (DimTarskiG≥‘3)) A10 Euclid's axiom (TarskiGE) A11 Axiom of continuity (TarskiGB) Our definition is split into 5 parts: congruence axioms TarskiGC (which metric spaces fulfill) betweenness axioms TarskiGB congruence and betweenness axioms TarskiGCB upper and lower dimension axioms DimTarskiG≥ axiom of Euclid / parallel postulate TarskiGE So our definition of a Tarskian Geometry includes the 3 axioms for the quaternary congruence relation (A1, A2, A3), the 3 axioms for the ternary betweenness relation (A6, A7, A11), and the 2 axioms of compatibility of the congruence and the betweenness relations (A4,A5). It does not include Euclid's axiom A10, nor the 2-dimensional axioms A8 (Lower dimension axiom) and A9 (Upper dimension axiom) so the number of dimensions of the geometry it formalizes is not constrained. Considering A2 as one of the 3 axioms for the quaternary congruence relation is somewhat conventional, because the transitivity of the congruence relation is automatically given by our choice to take the distance as this congruence relation in our definition of Tarski geometries. (Contributed by Thierry Arnoux, 24-Aug-2017.) (Revised by Thierry Arnoux, 27-Apr-2019.)
Assertion
Ref Expression
df-trkg TarskiG = ((TarskiGC ∩ TarskiGB) ∩ (TarskiGCB ∩ {𝑓[(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})}))
Distinct variable group:   𝑓,𝑝,𝑖,𝑥,𝑦,𝑧

Detailed syntax breakdown of Definition df-trkg
StepHypRef Expression
1 cstrkg 25129 . 2 class TarskiG
2 cstrkgc 25130 . . . 4 class TarskiGC
3 cstrkgb 25131 . . . 4 class TarskiGB
42, 3cin 3539 . . 3 class (TarskiGC ∩ TarskiGB)
5 cstrkgcb 25132 . . . 4 class TarskiGCB
6 vf . . . . . . . . . 10 setvar 𝑓
76cv 1474 . . . . . . . . 9 class 𝑓
8 clng 25136 . . . . . . . . 9 class LineG
97, 8cfv 5804 . . . . . . . 8 class (LineG‘𝑓)
10 vx . . . . . . . . 9 setvar 𝑥
11 vy . . . . . . . . 9 setvar 𝑦
12 vp . . . . . . . . . 10 setvar 𝑝
1312cv 1474 . . . . . . . . 9 class 𝑝
1410cv 1474 . . . . . . . . . . 11 class 𝑥
1514csn 4125 . . . . . . . . . 10 class {𝑥}
1613, 15cdif 3537 . . . . . . . . 9 class (𝑝 ∖ {𝑥})
17 vz . . . . . . . . . . . . 13 setvar 𝑧
1817cv 1474 . . . . . . . . . . . 12 class 𝑧
1911cv 1474 . . . . . . . . . . . . 13 class 𝑦
20 vi . . . . . . . . . . . . . 14 setvar 𝑖
2120cv 1474 . . . . . . . . . . . . 13 class 𝑖
2214, 19, 21co 6549 . . . . . . . . . . . 12 class (𝑥𝑖𝑦)
2318, 22wcel 1977 . . . . . . . . . . 11 wff 𝑧 ∈ (𝑥𝑖𝑦)
2418, 19, 21co 6549 . . . . . . . . . . . 12 class (𝑧𝑖𝑦)
2514, 24wcel 1977 . . . . . . . . . . 11 wff 𝑥 ∈ (𝑧𝑖𝑦)
2614, 18, 21co 6549 . . . . . . . . . . . 12 class (𝑥𝑖𝑧)
2719, 26wcel 1977 . . . . . . . . . . 11 wff 𝑦 ∈ (𝑥𝑖𝑧)
2823, 25, 27w3o 1030 . . . . . . . . . 10 wff (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))
2928, 17, 13crab 2900 . . . . . . . . 9 class {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))}
3010, 11, 13, 16, 29cmpt2 6551 . . . . . . . 8 class (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})
319, 30wceq 1475 . . . . . . 7 wff (LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})
32 citv 25135 . . . . . . . 8 class Itv
337, 32cfv 5804 . . . . . . 7 class (Itv‘𝑓)
3431, 20, 33wsbc 3402 . . . . . 6 wff [(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})
35 cbs 15695 . . . . . . 7 class Base
367, 35cfv 5804 . . . . . 6 class (Base‘𝑓)
3734, 12, 36wsbc 3402 . . . . 5 wff [(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})
3837, 6cab 2596 . . . 4 class {𝑓[(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})}
395, 38cin 3539 . . 3 class (TarskiGCB ∩ {𝑓[(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})})
404, 39cin 3539 . 2 class ((TarskiGC ∩ TarskiGB) ∩ (TarskiGCB ∩ {𝑓[(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})}))
411, 40wceq 1475 1 wff TarskiG = ((TarskiGC ∩ TarskiGB) ∩ (TarskiGCB ∩ {𝑓[(Base‘𝑓) / 𝑝][(Itv‘𝑓) / 𝑖](LineG‘𝑓) = (𝑥𝑝, 𝑦 ∈ (𝑝 ∖ {𝑥}) ↦ {𝑧𝑝 ∣ (𝑧 ∈ (𝑥𝑖𝑦) ∨ 𝑥 ∈ (𝑧𝑖𝑦) ∨ 𝑦 ∈ (𝑥𝑖𝑧))})}))
 Colors of variables: wff setvar class This definition is referenced by:  axtgcgrrflx  25161  axtgcgrid  25162  axtgsegcon  25163  axtg5seg  25164  axtgbtwnid  25165  axtgpasch  25166  axtgcont1  25167  tglng  25241  f1otrg  25551  eengtrkg  25665
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