| Step | Hyp | Ref | Expression | 
						
							| 1 |  | osumcllem.l |  |-  .<_ = ( le ` K ) | 
						
							| 2 |  | osumcllem.j |  |-  .\/ = ( join ` K ) | 
						
							| 3 |  | osumcllem.a |  |-  A = ( Atoms ` K ) | 
						
							| 4 |  | osumcllem.p |  |-  .+ = ( +P ` K ) | 
						
							| 5 |  | osumcllem.o |  |-  ._|_ = ( _|_P ` K ) | 
						
							| 6 |  | osumcllem.c |  |-  C = ( PSubCl ` K ) | 
						
							| 7 |  | osumcllem.m |  |-  M = ( X .+ { p } ) | 
						
							| 8 |  | osumcllem.u |  |-  U = ( ._|_ ` ( ._|_ ` ( X .+ Y ) ) ) | 
						
							| 9 |  | simp11 |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> K e. HL ) | 
						
							| 10 |  | simp2 |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> p e. A ) | 
						
							| 11 | 10 | snssd |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> { p } C_ A ) | 
						
							| 12 |  | simp12 |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> X C_ A ) | 
						
							| 13 | 3 4 | sspadd2 |  |-  ( ( K e. HL /\ { p } C_ A /\ X C_ A ) -> { p } C_ ( X .+ { p } ) ) | 
						
							| 14 | 9 11 12 13 | syl3anc |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> { p } C_ ( X .+ { p } ) ) | 
						
							| 15 |  | vex |  |-  p e. _V | 
						
							| 16 | 15 | snss |  |-  ( p e. ( X .+ { p } ) <-> { p } C_ ( X .+ { p } ) ) | 
						
							| 17 | 14 16 | sylibr |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> p e. ( X .+ { p } ) ) | 
						
							| 18 | 17 7 | eleqtrrdi |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> p e. M ) | 
						
							| 19 | 3 4 | sspadd1 |  |-  ( ( K e. HL /\ X C_ A /\ Y C_ A ) -> X C_ ( X .+ Y ) ) | 
						
							| 20 | 19 | 3ad2ant1 |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> X C_ ( X .+ Y ) ) | 
						
							| 21 |  | simp3 |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> -. p e. ( X .+ Y ) ) | 
						
							| 22 | 20 21 | ssneldd |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> -. p e. X ) | 
						
							| 23 |  | nelne1 |  |-  ( ( p e. M /\ -. p e. X ) -> M =/= X ) | 
						
							| 24 | 18 22 23 | syl2anc |  |-  ( ( ( K e. HL /\ X C_ A /\ Y C_ A ) /\ p e. A /\ -. p e. ( X .+ Y ) ) -> M =/= X ) |