Nuprl Lemma : r2-be-iff

u,v,x:ℝ^2.  (u_x_v ⇐⇒ ((¬(d(u;v) < d(u;x))) ∧ (d(u;v) < d(x;v)))) ∧ (r2-left(u;x;v) ∨ r2-left(u;v;x))))


Proof




Definitions occuring in Statement :  r2-left: r2-left(p;q;r) rv-be: a_b_c real-vec-dist: d(x;y) real-vec: ^n rless: x < y all: x:A. B[x] iff: ⇐⇒ Q not: ¬A or: P ∨ Q and: P ∧ Q natural_number: $n
Definitions unfolded in proof :  all: x:A. B[x] iff: ⇐⇒ Q and: P ∧ Q implies:  Q not: ¬A false: False uall: [x:A]. B[x] member: t ∈ T nat: le: A ≤ B less_than': less_than'(a;b) subtype_rel: A ⊆B prop: rev_implies:  Q or: P ∨ Q uimplies: supposing a guard: {T} uiff: uiff(P;Q) req_int_terms: t1 ≡ t2 top: Top cand: c∧ B stable: Stable{P} rv-be: a_b_c real-vec-sep: a ≠ b

Latex:
\mforall{}u,v,x:\mBbbR{}\^{}2.
    (u\_x\_v  \mLeftarrow{}{}\mRightarrow{}  ((\mneg{}(d(u;v)  <  d(u;x)))  \mwedge{}  (\mneg{}(d(u;v)  <  d(x;v))))  \mwedge{}  (\mneg{}(r2-left(u;x;v)  \mvee{}  r2-left(u;v;x))))



Date html generated: 2020_05_20-PM-01_02_31
Last ObjectModification: 2019_12_11-PM-00_19_03

Theory : reals


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