Metamath Proof Explorer


Theorem smatfval

Description: Value of the submatrix. (Contributed by Thierry Arnoux, 19-Aug-2020)

Ref Expression
Assertion smatfval KLMVKsubMat1ML=Mi,jifi<Kii+1ifj<Ljj+1

Proof

Step Hyp Ref Expression
1 elex MVMV
2 1 3ad2ant3 KLMVMV
3 coeq1 m=Mmi,jifi<kii+1ifj<ljj+1=Mi,jifi<kii+1ifj<ljj+1
4 3 mpoeq3dv m=Mk,lmi,jifi<kii+1ifj<ljj+1=k,lMi,jifi<kii+1ifj<ljj+1
5 df-smat subMat1=mVk,lmi,jifi<kii+1ifj<ljj+1
6 nnex V
7 6 6 mpoex k,lMi,jifi<kii+1ifj<ljj+1V
8 4 5 7 fvmpt MVsubMat1M=k,lMi,jifi<kii+1ifj<ljj+1
9 2 8 syl KLMVsubMat1M=k,lMi,jifi<kii+1ifj<ljj+1
10 breq2 k=Ki<ki<K
11 10 ifbid k=Kifi<kii+1=ifi<Kii+1
12 11 opeq1d k=Kifi<kii+1ifj<ljj+1=ifi<Kii+1ifj<ljj+1
13 12 mpoeq3dv k=Ki,jifi<kii+1ifj<ljj+1=i,jifi<Kii+1ifj<ljj+1
14 breq2 l=Lj<lj<L
15 14 ifbid l=Lifj<ljj+1=ifj<Ljj+1
16 15 opeq2d l=Lifi<Kii+1ifj<ljj+1=ifi<Kii+1ifj<Ljj+1
17 16 mpoeq3dv l=Li,jifi<Kii+1ifj<ljj+1=i,jifi<Kii+1ifj<Ljj+1
18 13 17 sylan9eq k=Kl=Li,jifi<kii+1ifj<ljj+1=i,jifi<Kii+1ifj<Ljj+1
19 18 adantl KLMVk=Kl=Li,jifi<kii+1ifj<ljj+1=i,jifi<Kii+1ifj<Ljj+1
20 19 coeq2d KLMVk=Kl=LMi,jifi<kii+1ifj<ljj+1=Mi,jifi<Kii+1ifj<Ljj+1
21 simp1 KLMVK
22 simp2 KLMVL
23 simp3 KLMVMV
24 6 6 mpoex i,jifi<Kii+1ifj<Ljj+1V
25 24 a1i KLMVi,jifi<Kii+1ifj<Ljj+1V
26 coexg MVi,jifi<Kii+1ifj<Ljj+1VMi,jifi<Kii+1ifj<Ljj+1V
27 23 25 26 syl2anc KLMVMi,jifi<Kii+1ifj<Ljj+1V
28 9 20 21 22 27 ovmpod KLMVKsubMat1ML=Mi,jifi<Kii+1ifj<Ljj+1