| Step | Hyp | Ref | Expression | 
						
							| 1 |  | lspindp5.v |  |-  V = ( Base ` W ) | 
						
							| 2 |  | lspindp5.n |  |-  N = ( LSpan ` W ) | 
						
							| 3 |  | lspindp5.w |  |-  ( ph -> W e. LVec ) | 
						
							| 4 |  | lspindp5.y |  |-  ( ph -> X e. V ) | 
						
							| 5 |  | lspindp5.x |  |-  ( ph -> Y e. V ) | 
						
							| 6 |  | lspindp5.u |  |-  ( ph -> U e. V ) | 
						
							| 7 |  | lspindp5.e |  |-  ( ph -> Z e. ( N ` { X , U } ) ) | 
						
							| 8 |  | lspindp5.m |  |-  ( ph -> -. Z e. ( N ` { X , Y } ) ) | 
						
							| 9 |  | ssel |  |-  ( ( N ` { X , U } ) C_ ( N ` { X , Y } ) -> ( Z e. ( N ` { X , U } ) -> Z e. ( N ` { X , Y } ) ) ) | 
						
							| 10 | 7 9 | syl5com |  |-  ( ph -> ( ( N ` { X , U } ) C_ ( N ` { X , Y } ) -> Z e. ( N ` { X , Y } ) ) ) | 
						
							| 11 | 8 10 | mtod |  |-  ( ph -> -. ( N ` { X , U } ) C_ ( N ` { X , Y } ) ) | 
						
							| 12 |  | lveclmod |  |-  ( W e. LVec -> W e. LMod ) | 
						
							| 13 | 3 12 | syl |  |-  ( ph -> W e. LMod ) | 
						
							| 14 |  | prssi |  |-  ( ( X e. V /\ Y e. V ) -> { X , Y } C_ V ) | 
						
							| 15 | 4 5 14 | syl2anc |  |-  ( ph -> { X , Y } C_ V ) | 
						
							| 16 |  | snsspr1 |  |-  { X } C_ { X , Y } | 
						
							| 17 | 16 | a1i |  |-  ( ph -> { X } C_ { X , Y } ) | 
						
							| 18 | 1 2 | lspss |  |-  ( ( W e. LMod /\ { X , Y } C_ V /\ { X } C_ { X , Y } ) -> ( N ` { X } ) C_ ( N ` { X , Y } ) ) | 
						
							| 19 | 13 15 17 18 | syl3anc |  |-  ( ph -> ( N ` { X } ) C_ ( N ` { X , Y } ) ) | 
						
							| 20 | 19 | biantrurd |  |-  ( ph -> ( ( N ` { U } ) C_ ( N ` { X , Y } ) <-> ( ( N ` { X } ) C_ ( N ` { X , Y } ) /\ ( N ` { U } ) C_ ( N ` { X , Y } ) ) ) ) | 
						
							| 21 |  | eqid |  |-  ( LSubSp ` W ) = ( LSubSp ` W ) | 
						
							| 22 | 21 | lsssssubg |  |-  ( W e. LMod -> ( LSubSp ` W ) C_ ( SubGrp ` W ) ) | 
						
							| 23 | 13 22 | syl |  |-  ( ph -> ( LSubSp ` W ) C_ ( SubGrp ` W ) ) | 
						
							| 24 | 1 21 2 | lspsncl |  |-  ( ( W e. LMod /\ X e. V ) -> ( N ` { X } ) e. ( LSubSp ` W ) ) | 
						
							| 25 | 13 4 24 | syl2anc |  |-  ( ph -> ( N ` { X } ) e. ( LSubSp ` W ) ) | 
						
							| 26 | 23 25 | sseldd |  |-  ( ph -> ( N ` { X } ) e. ( SubGrp ` W ) ) | 
						
							| 27 | 1 21 2 | lspsncl |  |-  ( ( W e. LMod /\ U e. V ) -> ( N ` { U } ) e. ( LSubSp ` W ) ) | 
						
							| 28 | 13 6 27 | syl2anc |  |-  ( ph -> ( N ` { U } ) e. ( LSubSp ` W ) ) | 
						
							| 29 | 23 28 | sseldd |  |-  ( ph -> ( N ` { U } ) e. ( SubGrp ` W ) ) | 
						
							| 30 | 1 21 2 13 4 5 | lspprcl |  |-  ( ph -> ( N ` { X , Y } ) e. ( LSubSp ` W ) ) | 
						
							| 31 | 23 30 | sseldd |  |-  ( ph -> ( N ` { X , Y } ) e. ( SubGrp ` W ) ) | 
						
							| 32 |  | eqid |  |-  ( LSSum ` W ) = ( LSSum ` W ) | 
						
							| 33 | 32 | lsmlub |  |-  ( ( ( N ` { X } ) e. ( SubGrp ` W ) /\ ( N ` { U } ) e. ( SubGrp ` W ) /\ ( N ` { X , Y } ) e. ( SubGrp ` W ) ) -> ( ( ( N ` { X } ) C_ ( N ` { X , Y } ) /\ ( N ` { U } ) C_ ( N ` { X , Y } ) ) <-> ( ( N ` { X } ) ( LSSum ` W ) ( N ` { U } ) ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 34 | 26 29 31 33 | syl3anc |  |-  ( ph -> ( ( ( N ` { X } ) C_ ( N ` { X , Y } ) /\ ( N ` { U } ) C_ ( N ` { X , Y } ) ) <-> ( ( N ` { X } ) ( LSSum ` W ) ( N ` { U } ) ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 35 | 20 34 | bitrd |  |-  ( ph -> ( ( N ` { U } ) C_ ( N ` { X , Y } ) <-> ( ( N ` { X } ) ( LSSum ` W ) ( N ` { U } ) ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 36 | 1 21 2 13 30 6 | ellspsn5b |  |-  ( ph -> ( U e. ( N ` { X , Y } ) <-> ( N ` { U } ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 37 | 1 2 32 13 4 6 | lsmpr |  |-  ( ph -> ( N ` { X , U } ) = ( ( N ` { X } ) ( LSSum ` W ) ( N ` { U } ) ) ) | 
						
							| 38 | 37 | sseq1d |  |-  ( ph -> ( ( N ` { X , U } ) C_ ( N ` { X , Y } ) <-> ( ( N ` { X } ) ( LSSum ` W ) ( N ` { U } ) ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 39 | 35 36 38 | 3bitr4d |  |-  ( ph -> ( U e. ( N ` { X , Y } ) <-> ( N ` { X , U } ) C_ ( N ` { X , Y } ) ) ) | 
						
							| 40 | 11 39 | mtbird |  |-  ( ph -> -. U e. ( N ` { X , Y } ) ) |