Nuprl Lemma : rsum-one
∀[n,m:ℤ].  (Σ{r1 | n≤k≤m} = if m <z n then r0 else r((m - n) + 1) fi )
Proof
Definitions occuring in Statement : 
rsum: Σ{x[k] | n≤k≤m}, 
req: x = y, 
int-to-real: r(n), 
ifthenelse: if b then t else f fi , 
lt_int: i <z j, 
uall: ∀[x:A]. B[x], 
subtract: n - m, 
add: n + m, 
natural_number: $n, 
int: ℤ
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
implies: P ⇒ Q, 
all: ∀x:A. B[x], 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
exists: ∃x:A. B[x], 
prop: ℙ, 
or: P ∨ Q, 
sq_type: SQType(T), 
guard: {T}, 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
not: ¬A, 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
req_witness, 
rsum_wf, 
int-to-real_wf, 
int_seg_wf, 
ifthenelse_wf, 
lt_int_wf, 
real_wf, 
subtract_wf, 
rmul_wf, 
eqtt_to_assert, 
assert_of_lt_int, 
rmul-zero, 
eqff_to_assert, 
equal_wf, 
bool_wf, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
rmul-identity1, 
req_functionality, 
rsum-constant2, 
req_weakening
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
natural_numberEquality, 
hypothesis, 
addEquality, 
independent_functionElimination, 
intEquality, 
isect_memberEquality, 
because_Cache, 
lambdaFormation, 
unionElimination, 
equalityElimination, 
productElimination, 
independent_isectElimination, 
dependent_pairFormation, 
equalityTransitivity, 
equalitySymmetry, 
promote_hyp, 
dependent_functionElimination, 
instantiate, 
voidElimination
Latex:
\mforall{}[n,m:\mBbbZ{}].    (\mSigma{}\{r1  |  n\mleq{}k\mleq{}m\}  =  if  m  <z  n  then  r0  else  r((m  -  n)  +  1)  fi  )
 Date html generated: 
2017_10_03-AM-08_59_53
 Last ObjectModification: 
2017_07_28-AM-07_39_15
Theory : reals
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