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Definition df-cgrg 28519
Description: Define the relation of congruence between shapes. Definition 4.4 of [Schwabhauser] p. 35. A "shape" is a finite sequence of points, and a triangle can be represented as a shape with three points. Two shapes are congruent if all corresponding segments between all corresponding points are congruent.

Many systems of geometry define triangle congruence as requiring both segment congruence and angle congruence. Such systems, such as Hilbert's axiomatic system, typically have a primitive notion of angle congruence in addition to segment congruence. Here, angle congruence is instead a derived notion, defined later in df-cgra 28816 and expanded in iscgra 28817. This does not mean our system is weaker; dfcgrg2 28871 proves that these two definitions are equivalent, and using the Tarski definition instead (given in [Schwabhauser] p. 35) is simpler. Once two triangles are proven congruent as defined here, you can use various theorems to prove that corresponding parts of congruent triangles are congruent (CPCTC). For example, see cgr3simp1 28528, cgr3simp2 28529, cgr3simp3 28530, cgrcgra 28829, and permutation laws such as cgr3swap12 28531 and dfcgrg2 28871.

Ideally, we would define this for functions of any set, but we will use words (see df-word 14553) in most cases.

(Contributed by Thierry Arnoux, 3-Apr-2019.)

Assertion
Ref Expression
df-cgrg cgrG = (𝑔 ∈ V ↦ {⟨𝑎, 𝑏⟩ ∣ ((𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)) ∧ (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))))})
Distinct variable group:   𝑎,𝑏,𝑔,𝑖,𝑗

Detailed syntax breakdown of Definition df-cgrg
StepHypRef Expression
1 ccgrg 28518 . 2 class cgrG
2 vg . . 3 setvar 𝑔
3 cvv 3480 . . 3 class V
4 va . . . . . . . 8 setvar 𝑎
54cv 1539 . . . . . . 7 class 𝑎
62cv 1539 . . . . . . . . 9 class 𝑔
7 cbs 17247 . . . . . . . . 9 class Base
86, 7cfv 6561 . . . . . . . 8 class (Base‘𝑔)
9 cr 11154 . . . . . . . 8 class
10 cpm 8867 . . . . . . . 8 class pm
118, 9, 10co 7431 . . . . . . 7 class ((Base‘𝑔) ↑pm ℝ)
125, 11wcel 2108 . . . . . 6 wff 𝑎 ∈ ((Base‘𝑔) ↑pm ℝ)
13 vb . . . . . . . 8 setvar 𝑏
1413cv 1539 . . . . . . 7 class 𝑏
1514, 11wcel 2108 . . . . . 6 wff 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)
1612, 15wa 395 . . . . 5 wff (𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ))
175cdm 5685 . . . . . . 7 class dom 𝑎
1814cdm 5685 . . . . . . 7 class dom 𝑏
1917, 18wceq 1540 . . . . . 6 wff dom 𝑎 = dom 𝑏
20 vi . . . . . . . . . . . 12 setvar 𝑖
2120cv 1539 . . . . . . . . . . 11 class 𝑖
2221, 5cfv 6561 . . . . . . . . . 10 class (𝑎𝑖)
23 vj . . . . . . . . . . . 12 setvar 𝑗
2423cv 1539 . . . . . . . . . . 11 class 𝑗
2524, 5cfv 6561 . . . . . . . . . 10 class (𝑎𝑗)
26 cds 17306 . . . . . . . . . . 11 class dist
276, 26cfv 6561 . . . . . . . . . 10 class (dist‘𝑔)
2822, 25, 27co 7431 . . . . . . . . 9 class ((𝑎𝑖)(dist‘𝑔)(𝑎𝑗))
2921, 14cfv 6561 . . . . . . . . . 10 class (𝑏𝑖)
3024, 14cfv 6561 . . . . . . . . . 10 class (𝑏𝑗)
3129, 30, 27co 7431 . . . . . . . . 9 class ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))
3228, 31wceq 1540 . . . . . . . 8 wff ((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))
3332, 23, 17wral 3061 . . . . . . 7 wff 𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))
3433, 20, 17wral 3061 . . . . . 6 wff 𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))
3519, 34wa 395 . . . . 5 wff (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗)))
3616, 35wa 395 . . . 4 wff ((𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)) ∧ (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))))
3736, 4, 13copab 5205 . . 3 class {⟨𝑎, 𝑏⟩ ∣ ((𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)) ∧ (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))))}
382, 3, 37cmpt 5225 . 2 class (𝑔 ∈ V ↦ {⟨𝑎, 𝑏⟩ ∣ ((𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)) ∧ (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))))})
391, 38wceq 1540 1 wff cgrG = (𝑔 ∈ V ↦ {⟨𝑎, 𝑏⟩ ∣ ((𝑎 ∈ ((Base‘𝑔) ↑pm ℝ) ∧ 𝑏 ∈ ((Base‘𝑔) ↑pm ℝ)) ∧ (dom 𝑎 = dom 𝑏 ∧ ∀𝑖 ∈ dom 𝑎𝑗 ∈ dom 𝑎((𝑎𝑖)(dist‘𝑔)(𝑎𝑗)) = ((𝑏𝑖)(dist‘𝑔)(𝑏𝑗))))})
Colors of variables: wff setvar class
This definition is referenced by:  iscgrg  28520  ercgrg  28525
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