Nuprl Lemma : right-angle-colinear2
∀e:BasicGeometry. ∀a,b,c,c':Point.  (Rabc ⇒ c ≠ b ⇒ Colinear(b;c;c') ⇒ Rabc')
Proof
Definitions occuring in Statement : 
basic-geometry: BasicGeometry, 
right-angle: Rabc, 
geo-colinear: Colinear(a;b;c), 
geo-sep: a ≠ b, 
geo-point: Point, 
all: ∀x:A. B[x], 
implies: P ⇒ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
prop: ℙ, 
uall: ∀[x:A]. B[x], 
subtype_rel: A ⊆r B, 
guard: {T}, 
uimplies: b supposing a, 
basic-geometry: BasicGeometry, 
stable: Stable{P}, 
not: ¬A, 
or: P ∨ Q, 
false: False, 
geo-eq: a ≡ b, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q
Lemmas referenced : 
geo-colinear_wf, 
euclidean-plane-structure-subtype, 
euclidean-plane-subtype, 
basic-geometry-subtype, 
subtype_rel_transitivity, 
basic-geometry_wf, 
euclidean-plane_wf, 
euclidean-plane-structure_wf, 
geo-primitives_wf, 
geo-sep_wf, 
right-angle_wf, 
geo-point_wf, 
stable__not, 
not_wf, 
false_wf, 
or_wf, 
stable__right-angle, 
minimal-double-negation-hyp-elim, 
right-angle_functionality, 
geo-eq_weakening, 
minimal-not-not-excluded-middle, 
right-angle-symmetry, 
right-angle-colinear, 
right-angle-trivial2
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
applyEquality, 
hypothesis, 
instantiate, 
independent_isectElimination, 
sqequalRule, 
because_Cache, 
functionEquality, 
dependent_functionElimination, 
independent_functionElimination, 
unionElimination, 
voidElimination, 
productElimination
Latex:
\mforall{}e:BasicGeometry.  \mforall{}a,b,c,c':Point.    (Rabc  {}\mRightarrow{}  c  \mneq{}  b  {}\mRightarrow{}  Colinear(b;c;c')  {}\mRightarrow{}  Rabc')
Date html generated:
2018_05_22-PM-00_02_33
Last ObjectModification:
2018_04_19-PM-07_41_39
Theory : euclidean!plane!geometry
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