Description: Two ways of saying a number is less than or equal to the minimum of two others. (Contributed by NM, 3-Aug-2007)
Ref | Expression | ||
---|---|---|---|
Assertion | lemin | |- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( A <_ if ( B <_ C , B , C ) <-> ( A <_ B /\ A <_ C ) ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | rexr | |- ( A e. RR -> A e. RR* ) |
|
2 | rexr | |- ( B e. RR -> B e. RR* ) |
|
3 | rexr | |- ( C e. RR -> C e. RR* ) |
|
4 | xrlemin | |- ( ( A e. RR* /\ B e. RR* /\ C e. RR* ) -> ( A <_ if ( B <_ C , B , C ) <-> ( A <_ B /\ A <_ C ) ) ) |
|
5 | 1 2 3 4 | syl3an | |- ( ( A e. RR /\ B e. RR /\ C e. RR ) -> ( A <_ if ( B <_ C , B , C ) <-> ( A <_ B /\ A <_ C ) ) ) |