theorem shlss (a b n: nat): $ a C_ b <-> shl a n C_ shl b n $;
Step | Hyp | Ref | Expression |
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1 | elshl | x e. shl a n <-> n <= x /\ x - n e. a |
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2 | elshl | x e. shl b n <-> n <= x /\ x - n e. b |
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3 | ssel | a C_ b -> x - n e. a -> x - n e. b |
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4 | 3 | anim2d | a C_ b -> n <= x /\ x - n e. a -> n <= x /\ x - n e. b |
5 | 2, 4 | syl6ibr | a C_ b -> n <= x /\ x - n e. a -> x e. shl b n |
6 | 1, 5 | syl5bi | a C_ b -> x e. shl a n -> x e. shl b n |
7 | 6 | iald | a C_ b -> A. x (x e. shl a n -> x e. shl b n) |
8 | 7 | conv subset | a C_ b -> shl a n C_ shl b n |
9 | sseq | shr (shl a n) n == a -> shr (shl b n) n == b -> (shr (shl a n) n C_ shr (shl b n) n <-> a C_ b) |
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10 | nseq | shr (shl a n) n = a -> shr (shl a n) n == a |
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11 | shrshlid | shr (shl a n) n = a |
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12 | 10, 11 | ax_mp | shr (shl a n) n == a |
13 | 9, 12 | ax_mp | shr (shl b n) n == b -> (shr (shl a n) n C_ shr (shl b n) n <-> a C_ b) |
14 | nseq | shr (shl b n) n = b -> shr (shl b n) n == b |
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15 | shrshlid | shr (shl b n) n = b |
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16 | 14, 15 | ax_mp | shr (shl b n) n == b |
17 | 13, 16 | ax_mp | shr (shl a n) n C_ shr (shl b n) n <-> a C_ b |
18 | shrss | shl a n C_ shl b n -> shr (shl a n) n C_ shr (shl b n) n |
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19 | 17, 18 | sylib | shl a n C_ shl b n -> a C_ b |
20 | 8, 19 | ibii | a C_ b <-> shl a n C_ shl b n |