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Mirrors > Home > MPE Home > Th. List > sseqtrd | Structured version Visualization version GIF version |
Description: Substitution of equality into a subclass relationship. (Contributed by NM, 25-Apr-2004.) |
Ref | Expression |
---|---|
sseqtrd.1 | ⊢ (𝜑 → 𝐴 ⊆ 𝐵) |
sseqtrd.2 | ⊢ (𝜑 → 𝐵 = 𝐶) |
Ref | Expression |
---|---|
sseqtrd | ⊢ (𝜑 → 𝐴 ⊆ 𝐶) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sseqtrd.1 | . 2 ⊢ (𝜑 → 𝐴 ⊆ 𝐵) | |
2 | sseqtrd.2 | . . 3 ⊢ (𝜑 → 𝐵 = 𝐶) | |
3 | 2 | sseq2d 3949 | . 2 ⊢ (𝜑 → (𝐴 ⊆ 𝐵 ↔ 𝐴 ⊆ 𝐶)) |
4 | 1, 3 | mpbid 231 | 1 ⊢ (𝜑 → 𝐴 ⊆ 𝐶) |
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