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Definition df-tru 1325
Description: Definition of  T., a tautology.  T. is a constant true. In this definition biid 228 is used as an antecedent, however, any true wff, such as an axiom, can be used in its place. (Contributed by Anthony Hart, 13-Oct-2010.)
Assertion
Ref Expression
df-tru  |-  (  T.  <->  (
ph 
<-> 
ph ) )

Detailed syntax breakdown of Definition df-tru
StepHypRef Expression
1 wtru 1322 . 2  wff  T.
2 wph . . 3  wff  ph
32, 2wb 177 . 2  wff  ( ph  <->  ph )
41, 3wb 177 1  wff  (  T.  <->  (
ph 
<-> 
ph ) )
Colors of variables: wff set class
This definition is referenced by:  tru  1327  uunT1  28605
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