| Step | Hyp | Ref | Expression | 
						
							| 1 |  | spansnsh |  | 
						
							| 2 |  | spansnsh |  | 
						
							| 3 |  | shscl |  | 
						
							| 4 | 1 2 3 | syl2an |  | 
						
							| 5 | 4 | adantr |  | 
						
							| 6 | 1 2 | anim12i |  | 
						
							| 7 |  | spansnid |  | 
						
							| 8 |  | spansnid |  | 
						
							| 9 | 7 8 | anim12i |  | 
						
							| 10 |  | shsva |  | 
						
							| 11 | 6 9 10 | sylc |  | 
						
							| 12 | 11 | adantr |  | 
						
							| 13 |  | simpr |  | 
						
							| 14 |  | elspansn3 |  | 
						
							| 15 | 5 12 13 14 | syl3anc |  | 
						
							| 16 | 15 | ex |  | 
						
							| 17 | 16 | ssrdv |  | 
						
							| 18 |  | df-pr |  | 
						
							| 19 | 18 | fveq2i |  | 
						
							| 20 |  | snssi |  | 
						
							| 21 |  | snssi |  | 
						
							| 22 |  | spanun |  | 
						
							| 23 | 20 21 22 | syl2an |  | 
						
							| 24 | 19 23 | eqtr2id |  | 
						
							| 25 | 17 24 | sseqtrd |  |