‘Real Differences between OT and CRDT’ Series by Chengzheng Sun, et. al.

“[1810.02137] Real Differences between OT and CRDT for Co-Editors” was discussed about on Hacker News. This paper, submitted to ArXiv on October 2018, seems to be the oldest of the series of papers by the same authors with seemingly overlapping content. In fact, ArXiv attaches a note to that effect. Below are the newer papers, all of which were last revised on 10 Jun 2020 and are labeled “v2”:

• “[1905.01518] Real Differences between OT and CRDT under a General Transformation Framework for Consistency Maintenance in Co-Editors“
• “[1905.01517] Real Differences between OT and CRDT in Building Co-Editing Systems and Real World Applications“
• “[1905.01302] Real Differences between OT and CRDT in Correctness and Complexity for Consistency Maintenance in Co-Editors“

The first one is supposedly a revised version of “Real Differences between OT and CRDT under a General Transformation Framework for Consistency Maintenance in Co-Editors” in Proceedings of the ACM on Human-Computer Interaction, January 2020 Article No.: 06 https://doi.org/10.1145/3375186. There is a rebuttal in “Response to ‘Real Differences between OT and CRDT for Co-Editors’ · GitHub.”

Cheap Cell Phone Plans in the US Primarily for Texts Only

Page Plus logo

US Paypal is giving me another headache, by insisting again that I give them a cell phone number to which they can send a verification code. The problem is I have none. I had the same issue before, but at that time I resolved the problem by calling their customer service and having them turn off their two-phase authentication. I wrote the following articles on the topic at that time:

• “Working Around The Can’t-Receive-Verification-SMS Issue“
• “米サービスが本人認証のために送るSMSが受け取れる携帯番号取得法“
• “US Mobile“

But exactly the same issue occurred again. So I had to call them yet again. They had me on hold for almost exactly one hour. The rep sent me a link via email from which I could change my password and with that I could log in and make the transaction I needed to make. However, once I was logged out, I couldn’t log in again, and they again ask for a phone number for them to send a text message for verification. The rep said it was a rare situation but here I am again. Is this the dance I need to do every time I need to log into Paypal from now on?

God I hope not! So I researched some more.

• “What’s the cheapest US SIM card that only has text(sms)? Not really looking for calls or data. : NoContract“
• “Cheapest PayGo plan for emergency calls/data? (No Sprint coverage) : NoContract“

Page Plus Cellular’s No Contract Prepaid Plans include $10 Standard Plan, valid for 120 days. In reality more like $13 every 120 days so roughly $40 for a year. I need to use only one or two texts a month, so each text would cost more than $2 — that’s a heck of an expensive text. But this is certainly an option when push comes to shove.

Interestingly, 4G Pay-As-You-Go Plans is cheaper than 3G Pay-As-You-Go Plans. BYOP 3-in-1 SIM Activation Kit | Page Plus Cellular is $0.99.

Page Plus Cellular is a Verizon MVNO. For LTE (4G), Verizon uses bands 2, 4, 5, 13, 66, with 13 being the primary one. There is zero overlapping with LTE bands used in Japan. Cell phone models made specifically for the Japanese market may support only part of Verizon’s bands at best.

For the band usage in the US, see “Cheat sheet: which 4G LTE bands do AT&T, Verizon, T-Mobile and Sprint use in the USA? – Business.”