| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ply1ass23l.p |  |-  P = ( Poly1 ` R ) | 
						
							| 2 |  | ply1ass23l.t |  |-  .X. = ( .r ` P ) | 
						
							| 3 |  | ply1ass23l.b |  |-  B = ( Base ` P ) | 
						
							| 4 |  | ply1ass23l.k |  |-  K = ( Base ` R ) | 
						
							| 5 |  | ply1ass23l.n |  |-  .x. = ( .s ` P ) | 
						
							| 6 |  | eqid |  |-  ( 1o mPwSer R ) = ( 1o mPwSer R ) | 
						
							| 7 |  | 1on |  |-  1o e. On | 
						
							| 8 | 7 | a1i |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> 1o e. On ) | 
						
							| 9 |  | simpl |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> R e. Ring ) | 
						
							| 10 |  | eqid |  |-  { f e. ( NN0 ^m 1o ) | ( `' f " NN ) e. Fin } = { f e. ( NN0 ^m 1o ) | ( `' f " NN ) e. Fin } | 
						
							| 11 |  | eqid |  |-  ( 1o mPoly R ) = ( 1o mPoly R ) | 
						
							| 12 | 1 11 2 | ply1mulr |  |-  .X. = ( .r ` ( 1o mPoly R ) ) | 
						
							| 13 | 11 6 12 | mplmulr |  |-  .X. = ( .r ` ( 1o mPwSer R ) ) | 
						
							| 14 |  | eqid |  |-  ( Base ` ( 1o mPwSer R ) ) = ( Base ` ( 1o mPwSer R ) ) | 
						
							| 15 |  | eqid |  |-  ( Base ` ( 1o mPoly R ) ) = ( Base ` ( 1o mPoly R ) ) | 
						
							| 16 | 11 6 15 14 | mplbasss |  |-  ( Base ` ( 1o mPoly R ) ) C_ ( Base ` ( 1o mPwSer R ) ) | 
						
							| 17 | 1 3 | ply1bascl2 |  |-  ( X e. B -> X e. ( Base ` ( 1o mPoly R ) ) ) | 
						
							| 18 | 16 17 | sselid |  |-  ( X e. B -> X e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 19 | 18 | 3ad2ant2 |  |-  ( ( A e. K /\ X e. B /\ Y e. B ) -> X e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 20 | 19 | adantl |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> X e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 21 | 1 3 | ply1bascl2 |  |-  ( Y e. B -> Y e. ( Base ` ( 1o mPoly R ) ) ) | 
						
							| 22 | 16 21 | sselid |  |-  ( Y e. B -> Y e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 23 | 22 | 3ad2ant3 |  |-  ( ( A e. K /\ X e. B /\ Y e. B ) -> Y e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 24 | 23 | adantl |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> Y e. ( Base ` ( 1o mPwSer R ) ) ) | 
						
							| 25 | 1 11 5 | ply1vsca |  |-  .x. = ( .s ` ( 1o mPoly R ) ) | 
						
							| 26 | 11 6 25 | mplvsca2 |  |-  .x. = ( .s ` ( 1o mPwSer R ) ) | 
						
							| 27 |  | simpr1 |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> A e. K ) | 
						
							| 28 | 6 8 9 10 13 14 20 24 4 26 27 | psrass23l |  |-  ( ( R e. Ring /\ ( A e. K /\ X e. B /\ Y e. B ) ) -> ( ( A .x. X ) .X. Y ) = ( A .x. ( X .X. Y ) ) ) |