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Metamath Proof Explorer

Theorem ismndo1

Description: The predicate "is a monoid". (Contributed by FL, 2-Nov-2009) (Revised by Mario Carneiro, 22-Dec-2013) (New usage is discouraged.)

Ref Expression
Hypothesis ismndo1.1 ⊢ 𝑋 = dom dom 𝐺
Assertion ismndo1 ( 𝐺 ∈ 𝐴 → ( 𝐺 ∈ MndOp ↔ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) )

Proof

Step Hyp Ref Expression
1 ismndo1.1 ⊢ 𝑋 = dom dom 𝐺
2 1 ismndo ⊢ ( 𝐺 ∈ 𝐴 → ( 𝐺 ∈ MndOp ↔ ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) )
3 1 smgrpmgm ⊢ ( 𝐺 ∈ SemiGrp → 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 )
4 3 ad2antrl ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 )
5 1 smgrpassOLD ⊢ ( 𝐺 ∈ SemiGrp → ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) )
6 5 ad2antrl ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) )
7 simprr ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) )
8 4 6 7 3jca ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) )
9 3simpa ⊢ ( ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) → ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ) )
10 1 issmgrpOLD ⊢ ( 𝐺 ∈ 𝐴 → ( 𝐺 ∈ SemiGrp ↔ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ) ) )
11 9 10 imbitrrid ⊢ ( 𝐺 ∈ 𝐴 → ( ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) → 𝐺 ∈ SemiGrp ) )
12 11 imp ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → 𝐺 ∈ SemiGrp )
13 simpr3 ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) )
14 12 13 jca ⊢ ( ( 𝐺 ∈ 𝐴 ∧ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) → ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) )
15 8 14 impbida ⊢ ( 𝐺 ∈ 𝐴 → ( ( 𝐺 ∈ SemiGrp ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ↔ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) )
16 2 15 bitrd ⊢ ( 𝐺 ∈ 𝐴 → ( 𝐺 ∈ MndOp ↔ ( 𝐺 : ( 𝑋 × 𝑋 ) ⟶ 𝑋 ∧ ∀ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ∀ 𝑧 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) 𝐺 𝑧 ) = ( 𝑥 𝐺 ( 𝑦 𝐺 𝑧 ) ) ∧ ∃ 𝑥 ∈ 𝑋 ∀ 𝑦 ∈ 𝑋 ( ( 𝑥 𝐺 𝑦 ) = 𝑦 ∧ ( 𝑦 𝐺 𝑥 ) = 𝑦 ) ) ) )