Description: The singletonization is included in the tagging. (Contributed by BJ, 6-Oct-2018)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bj-sngltagi | ⊢ ( 𝐴 ∈ sngl 𝐵 → 𝐴 ∈ tag 𝐵 ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | bj-snglsstag | ⊢ sngl 𝐵 ⊆ tag 𝐵 | |
| 2 | 1 | sseli | ⊢ ( 𝐴 ∈ sngl 𝐵 → 𝐴 ∈ tag 𝐵 ) |